New 1:14 twist 30-06

[Nobade]

Thanks to some suggestions here, I finally got my 1:14 twist Remington 30-06 finished up. Blueprinted action, refinished ADL stock, Brux barrel, Manson match reamer, pillar bedded with a Vortex scope on top. I got to shoot it today for the firat time, and I think I'm going to like it! I was using Ranch Dog 165gr. tumble lube boolits, and IMR 4895. Started with 38gr, and worked up to 47gr. Best groups were at 44 gr, with 5 shots into just over 1/2 inch at 100 yards. I didn't chronograph it, but it has to be running around 2450 fps according to Quickload. For shooting a bullet completely not optimized to the rifle, lubed with liquid alox, I am impressed. Even the top loads I tried held 1.5 MOA and I still had a black bore. This slow twist stuff really works! There's no way I could ever get a normal 1:10 30-06 rifle to do that. Next time out I'll try some paper patched loads and some RCBS 165SIL with real lube. Should be fun to see what this rig is ultimately capable of. Now I am wishing I had gone with 1:16 twist, but this will keep me entertained for some time as it is.

-Nobade

[Dthunter]

Good job!
Well chosen barrel twist!
Be sure to try the slower powders like 4350,4831 with some heavier bullets. The 311299,311644 should really shoot well! My 308win loves them.
Good luck and keep us posted!

[Larry Gibson]

Love it when a "plan" comes together. Something to be said for keeping cast bullets, especially those "shooting a bullet completely not optimized to the rifle", under the RPM threshold at high velocity.

Larry Gibson

[Green Lizzard]

larry after 40 years of shooting 30-30 cast single shot, lever, bolt action, pump action 10 twist and 12 twist i am 100% sold on the rpm threshold

[Larry Gibson]

larry after 40 years of shooting 30-30 cast single shot, lever, bolt action, pump action 10 twist and 12 twist i am 100% sold on the rpm threshold

Most CF rifle cast bullet shooters are very aware of the existence of the RPM threshold. They may not call it that but whatever they call it it's the same. A few die hard hold outs who won't admit it's there but most are coming around.

Larry Gibson

[45 2.1]

Well Larry, since you mentioned me among "A few die hard hold outs", I'll respond. Nobade posted this in part:

Blueprinted action, refinished ADL stock, Brux barrel, Manson match reamer, pillar bedded with a Vortex scope on top. I got to shoot it today for the first time, and I think I'm going to like it! I was using Ranch Dog 165gr. tumble lube boolits, and IMR 4895. Started with 38gr, and worked up to 47gr. Best groups were at 44 gr, with 5 shots into just over 1/2 inch at 100 yards. I didn't chronograph it, but it has to be running around 2450 fps according to Quickload. For shooting a bullet completely not optimized to the rifle, lubed with liquid alox, I am impressed. Even the top loads I tried held 1.5 MOA and I still had a black bore. This slow twist stuff really works! There's no way I could ever get a normal 1:10 30-06 rifle to do that.

Seems like he built a custom rifle, along a benchrester's methods, to achieve that. Most bench rest rifles built like that shoot quite well. The altered color text above shows those items. The comparison to a standard production factory rifle should show that......... Twist has little to do with it, when you know what your doing, since that level of performance can be done with standard factory rifles in the normal 10" twist.

[Char-Gar]

You have a double throw down, double clutching, E flat. super dooper cast bullet rifle.

I owned for about 20 years an 03 Springfield (30-06) with a 1-14 Phifer barrel. It was the best shooting cast bullet rifle I ever shot.

It would shoot up to 165 grain jackets bullets with wonderful accuracy, 180 grain bullets not so much.

Many years ago, I figured out a slower twist barrel treated cast bullets better than a faster twist as long as the bullet was stabilized. We have known this for generations. A slower twist barrel can push cast bullets faster with accuracy than one with a slower barrel. There is no secret mojo that enables a faster twist barrel to shoot the same bullet as fast as a slower twist barrel with equal accuracy.

I never heard of the RPM stuff until a few years ago, but I proved the effect of slower vs. faster twist to myself over and over again.

[45 2.1]

There is no secret mojo that enables a faster twist barrel to shoot the same bullet as fast as a slower twist barrel with equal accuracy.

Nothing secret about it at all to get that accuracy mentioned by the OP in a 10 twist, but it is not discussed here other than by Starmetal and I (the bench rest folks understand the basic principle quite well). It does depend on what you know also.... after all, your signature line says "It is just my opinion based on my experience and knowledge. Your mileage may vary." Mileage varies a lot here, wouldn't you say............

[Dthunter]

Most CF rifle cast bullet shooters are very aware of the existence of the RPM threshold. They may not call it that but whatever they call it it's the same. A few die hard hold outs who won't admit it's there but most are coming around.

Larry Gibson

Absolutely Larry! There is simply a physical limit in/to every alloys tensile strength potential. Finding it, and making it work to your best advantage is the key.

[Nobade]

Wow, I didn't know this would stir up so much discussion! I will say though that I have a M1 with a 1:10 barrel on it and the chamber is cut with the same reamer. Now bearing in mind this is an M1 and not a bolt gun, and wears regular iron sights, it is still a lot fussier about cast boolit loads than the slow twist Remington. It does shoot very well after I found a load it likes, but only at 2100 fps and only this particular load. I don't have enough trigger time with the Remington yet, but seeing how it grouped reasonably well with a huge range of loads already I think it is going to be quite easy to work with.

Thanks for the comments, keep 'em coming!

-Nobade

[TXGunNut]

Congrats, sounds like a nice rifle. Computer issues tonight, pics of your new baby didn't download. ;-)

[Nrut]

Hi Nobabe,
Does your reamer cut a tapered neck or a straight neck?
ie. can you neck turn your cases?
Thanks

[nanuk]

...Twist has little to do with it, when you know what your doing, since that level of performance can be done with standard factory rifles in the normal 10" twist.


I thought this thread would raise your hackles.

but I do have a serious question:
Why is often stated that with the same guns, it is easier to get accuracy at higher velocity with a slower twist vice a faster twist, all else being equal?
Surely it can't be a coincidence?

[45 2.1]

Wow, I didn't know this would stir up so much discussion! I will say though that I have a M1 with a 1:10 barrel on it and the chamber is cut with the same reamer. Now bearing in mind this is an M1 and not a bolt gun, and wears regular iron sights, it is still a lot fussier about cast boolit loads than the slow twist Remington. Nobade

Nobade, it sounds like you have a fine rifle... enjoy it. The Garand will go in the high 2200 to the lower 2300s with better than ball accuracy if you learn how.


I thought this thread would raise your hackles.

but I do have a serious question:
Why is often stated that with the same guns, it is easier to get accuracy at higher velocity with a slower twist vice a faster twist, all else being equal?
Surely it can't be a coincidence?

No hackles at all nanuk, I just find poor information from the flat earth society redundant (you can't sail but so far or you'll fall off) since the world is round (and has progressed farther than 80's technology that's being touted).
There are enough myths and bad information to wade through without this stuff being touted as proven. The point is that twist makes little difference (within the normal factory twist usual choices) if you pay attention to the pertinent things that matter.

On your question..... it entails a lot of jacketed experimentation. Several gun writers have taken most available samples the cartridge comes in along with the entire twist range with quite a few factory loads... the results were the faster twists shot them all better.......... With cast?.... it entirely revolves around boolit type, fit and tolerances along with a rifle that is put together reasonably well (quite a few have serious problems). You can get accuracy easier with some things, but you limit your choices by doing so and the range of loads you can shoot diminishes with a slow twist. That is well proven.

[Dthunter]

Have any of you cast boolet shooters ever pushed a 200 grain boolet at 2350-2400fps in a 308 (with a 1:10" twist), AND shot it inside 1-1/2 to 2MOA out to 6-700+ yards? Repeatedly? I sure tried!
(Paper patched boolets dont apply here)

I have tired MANY times with a few different rifles. No such luck.

As soon as I switched to a 1:12" twist, everything changed!

I even went so far as to get/buy a second rifle in 1:12" twist to compare. VERY similar results!
Over a few thousand rounds of testing, I am more than convinced that the twist rate and acceleration/rate of pressure imparted to a boolet during the initial stages of the firing sequence govern everything that follows.

It stands to reason that if you impart a given pressure to a boolet base at a given rate.

And, if you compare the stress that "ANY" alloy experiences at this pressure, and compare the torque values on the boolet alloy (shear strength value) between a 1:10" and a 1:12" twist has on a boolet, the 1:12" twist will ALWAYS creat less torsional/torque on a boolet. It is simply slower.

When a reloader loads for high performance/pressure (velocity with accuacy) on a given boolet, the 1:10" twist will most certainly encounter its physical limit before a 1:12" twist will "given the same load parameters." Its just physics really.

I am not saying that 1:10" twist cannot reach this velocity. Some shooters have. But, the exception does not make " THE RULE".

I am saying that to reach these velocities with accuracy in a 1:10"
Twist, the stars have to align wayyy better!

Hopefully my explanation was clear and understandable.

The 1:14" twist would certainly be interesting to experiment with!

[Green Lizzard]

maybe if you had a perfect mold and alloy optimized for your (perfect gun), but i shoot a lot of lees in old 788

[Nobade]

Hi Nobabe,
Does your reamer cut a tapered neck or a straight neck?
ie. can you neck turn your cases?
Thanks

It has some taper to it. I originally wanted to get a reamer with a straight neck for this rifle, but time and money constraints prevented that from happening and since I had this nearly brand new reamer that the shop recently bought I went ahead and used that.

-Nobade

[Larry Gibson]

Dthunter is obviously of the "flat earth society" in that he understands and believes in the laws of physics. I am to obviously. This has all been hashed out so many times. Nobade is obviously pleased with his rifle and I'm sure he will find it quite fun and useful. I have, as I'm sure most know, done a lot of comparison testing both of velocity and pressures in 10, 12 and 14" twist .308Ws. I've done a lot of the same with 7, 9, 12 and 14" twist .223 Remingtons. The RPM threshold is real. Those that claim it is not have yet to demonstrate such by shooting their claimed moa and sub moa cast bullet groups from 10" or faster twist rifles at their claimed 2400+ fps velocities. I am more than happy to demonstrate 1 1/2 moa accuracy with the 311466 at 2600 fps from my 14" twist Palma rifle to anyone any time. 45 2.1 and his banned cohort are not.....there in lay the "myths and bad information" of which he speaks.

Many, many cast bullet shooters come up against the RPM threshold all the time. They know it's there and understand. The RPM threshold can be pushed upwards but as 45 2.1 truthfully says; "it entirely revolves around boolit type, fit and tolerances" and additionally the acceleration rate through the use of slower burning propellants. As to 45 2.1s claim of; "along with a rifle that is put together reasonably well (quite a few have serious problems)" which I find ludicrous in that he and his cohort claim to shoot sub moa cast bullet accuracy at HV in every rifle including milsurps.......

As to limiting your choices.....perhaps 45 2.1 should get himself a 14" twist '06 or .308W.......he may find that at 2400 - 2600+ fps they stabilized cast bullets of 118 gr (lightest I've shot in mine) to 200 gr 311299s. If that "limits your choices" then so be it, call me a "redundant" charter member of the flat earth society. If you are building a rifle such as Nobade has then why "limit" yourself with the frustration of a fast twist barrel when the slower twist is proven to shoot so well without all the witchcraft, magic and old wives tales 45 2.1 tells us is necessary with the fast twists barrels.

Larry Gibson

[nanuk]

The earth isn't flat???? Next you will tell me that Mankind creates global warming and oil production causes earthquakes!

[Nrut]

The earth isn't flat???? Next you will tell me that Mankind creates global warming and oil production causes earthquakes!
Well where you live the earth is flat! :p

[Char-Gar]

The fellow who doesn't think the earth is flat has never been to Kansas.

[45 2.1]

Many, many cast bullet shooters come up against the RPM threshold all the time. They know it's there and understand. The RPM threshold can be pushed upwards but as 45 2.1 truthfully says; "it entirely revolves around boolit type, fit and tolerances" and additionally the acceleration rate through the use of slower burning propellants. As to 45 2.1s claim of; "along with a rifle that is put together reasonably well (quite a few have serious problems)" which I find ludicrous in that he and his cohort claim to shoot sub moa cast bullet accuracy at HV in every rifle including milsurps.......

As to limiting your choices.....perhaps 45 2.1 should get himself a 14" twist '06 or .308W.......he may find that at 2400 - 2600+ fps they stabilized cast bullets of 118 gr (lightest I've shot in mine) to 200 gr 311299s.
Larry Gibson


I owned for about 20 years an 03 Springfield (30-06) with a 1-14 Phifer barrel. It was the best shooting cast bullet rifle I ever shot.

It would shoot up to 165 grain jackets bullets with wonderful accuracy, 180 grain bullets not so much.

Perhaps you should tell Char-Gar his rifle will shoot the 165 gr. and above better than he said. Seems his results didn't match yours.

All most people understand is that they can't get accuracy the way they're doing things above a certain level. Tolerances, not an unsubstantiated notion is the cause. Most folks who don't understand why they're having a problem will latch onto something that sounds reasonable........ The same way you did. Remove the poor tolerances and the problem simply disappears.

goodsteel is the resident gunsmith who deals in very small tolerances in barrel work. Ask him about some of the factory barrels he encounters. Really atrocious barrels...........

If you or anyone else wants to put a custom barrel on his firearm, spend that money then.... anyway you want, but some or most of the folks here would be quite hard pressed to do that too often. You tell them they can push a fictitious made up name for an equally unproven theory (I can supply the link to where you said this in a post BTW... and anyone is welcome to PM me for it) to get accuracy over about 1800 or so by buying a slow twist barrel. Yep, just trade money for learning something...........works every time. Government does that a lot and we all see where that goes. The point is that accuracy happens when you start and keep a cast boolit straight in the barrel, from loading to exit of the barrel instead of tipping it right in the cartridge neck upon ignition and sending it down the barrel out of line to produce the symptoms you've described.

[nanuk]

Well where you live the earth is flat! :p

the "Gap" is flat all right!

[TXGunNut]

I didn't understand the RPM threshold concept until I ran into it twice trying to get a 30-30 to push a boolit thru a 1/10 twist tube @ factory load velocities. Tried lots of things, didn't work, didn't know why. Pretty ugly "groups"; blamed the rifle, blamed the scope. Scope had issues but it was the load all along. Shooting buddy was shooting the same boolit @ 1600 fps and getting awesome groups, I backed off to 1800 and groups greatly improved.
I may be wrong but it seems to me it's more about physics than it is about careful blueprinting of rifles and loads. We can't get something as stupid as Obamacare repealed, not a chance of changing the laws of physics.

[frnkeore]

I'm a competitive target shooter in ASSRA & ISSA and while I shoot at velocitys under 1650 fps, I always match the bullet length to the twist rate in my competion rifles and use the slowest twist that keeps the bullet point on at 200 yards. By that, I'm always under the so called "threshold", I do have some points and questions relating to this though.

1. I have seen excellent scores and groups shot with 30 cal, 10 twist, ~2000 fps match rifles in CBA matches.

2. If it can be done in even one rifle, reliably, it can be done in any 10 twist with the same setup.

3. A match chambering and quality barrel can and will shoot better than a "factory" chambering and barrel. The throat means almost everything with cast bullets. You will NEVER find a match winning cast bullet target rifle with a "factory" throat.

4. You really need to define accuracy when it comes to these blanket statements. What is the inaccuracy that you speak of when the bullet crosses the "threashold" or what is the maximum accuracy to be expected of bullets that cross the threshold? I see threshold as a subjective term that can be defined in any number of ways and thus a fairly safe term to use if other's results doesn't fit your ideology.

5. I have never seen it (threshold) defined regarding what actually happens to the cast bullet that causes the inaccuracy. Since PP bullets seem to be considered immune to it, even though they are cast also, why aren't they subject to it?.

6. I have only one experiance in this matter. Scoped M48, original chambering and barrel, floated 9.5 twist barrel in a slightly shorten stock. WC 852, 2157 fps, original Lyman 323471, 215 gr w/GC bullet in #2 alloy, reformed '06 LC brass. It will average 2", five shot groups (4 five shot average) at 100 yards. What would the groups be if it was under the "threshold"?

Frank

[Larry Gibson]

frnkeore

5. I have never seen it (threshold) defined regarding what actually happens to the cast bullet that causes the inaccuracy. Since PP bullets seem to be considered immune to it, even though they are cast also, why aren't they subject to it?.

Obviously your coming in late on the RPM threshold discussion. I have discussed and answered the question as to the cause of inaccuracy (centrifugal force) when the cast bullet crosses the RPM threshold. The PP'd cast bullet is indeed subject to the RPM threshold especially with softer alloys. However many times the RPM threshold will be above the velocity/RPM attainable by the cartridge/bullet/barrel length combination used. The RPM threshold will occur at a higher velocity/RPM because the PP'd cast bullet is much better supported in the barrel and maintains it's balance much better and to a much higher acceleration rate.

A search of a lot of my posts in numerous threads will give you a much more detailed description of how higher RPM can cause inaccuracy. A study of ballistics will do the same or simply reading the accuracy section in the Hornady manuals will provide a simplified answer.

6. I have only one experiance in this matter. Scoped M48, original chambering and barrel, floated 9.5 twist barrel in a slightly shorten stock. WC 852, 2157 fps, original Lyman 323471, 215 gr w/GC bullet in #2 alloy, reformed '06 LC brass. It will average 2", five shot groups (4 five shot average) at 100 yards. What would the groups be if it was under the "threshold"?

May be that your load is still under the RPM threshold for that bullet/load combination. Question is does the same load average the same 2 moa at 200 yards? If not and there is non linear expansion of the groups then that load has exceeded the RPM threshold. The farther over the RPM threshold the larger the non linear expansion will be. Going over the RPM threshold does not mean the bullet loses stability and all accuracy is lost.

That 323471 is a very well designed Loverin style bullet and one can push the RPM threshold upwards with it. I can push it also to 2150 fps with 2 moa accuracy and be right at the RPM threshold. It has one of the highest BCs for cast bullets that will shoot well at higher velocity and is a favorite of mine for longer range shooting (600 yards). However, if I back it off to 1850 fps it shoots 10 shot groups right at 1 moa at 100 and 200 yards out of my own 24/47.

Larry Gibson

[frnkeore]

1. I have seen excellent scores and groups shot with 30 cal, 10 twist, ~2000 fps match rifles in CBA matches.

In support to the above statement, I offer this, shot at the CBA Nationals, this year:

http://www.castbulletassoc.org/br/2013/pdf/nationals/nationals.pdf

Craig, Frank
Soquel, CA

HVY class

Cartridge, 30BR

Barrel, Shilen, 26" lg, 10 twist

Action, Shilen DGA

Scope, Tasco 36X

Weight, 13lb 14oz

Mold design, Eagan 215gr

Alloy, Lino

Base dia. .310, Nose, .300

Lube, Texaco Turax

Powder, N 135, Charge 28.0, Primer Rem 7 1/2

Velocity, 2020 fps chronographed


Score targets

199 5x 100 yds
184 1x 200 yds
383 6x combined score

5 shot groups

0.564 100 yds
1.490 200 yds
0.654 MOA for 100 & 200 yds combined

10 shot groups

0.677 100 yds
2.356 200 yds
0.928 MOA for 100 & 200 yds combined

How is this possible?

4. You really need to define accuracy when it comes to these blanket statements. What is the inaccuracy that you speak of when the bullet crosses the "threashold" or what is the maximum accuracy to be expected of bullets that cross the threshold? I see threshold as a subjective term that can be defined in any number of ways and thus a fairly safe term to use if other's results doesn't fit your ideology.

You didn't address the above. But, what you say below, seems to comfirm my last sentence.

Obviously your coming in late on the RPM threshold discussion. I have discussed and answered the question as to the cause of inaccuracy (centrifugal force) when the cast bullet crosses the RPM threshold. The PP'd cast bullet is indeed subject to the RPM threshold especially with softer alloys. However many times the RPM threshold will be above the velocity/RPM attainable by the cartridge/bullet/barrel length combination used. The RPM threshold will occur at a higher velocity/RPM because the PP'd cast bullet is much better supported in the barrel and maintains it's balance much better and to a much higher acceleration rate.

I'm probably not the only one that has come late to this theory so, I'm sure others would also like to know.

The RPM threshold will occur at a higher velocity/RPM because the PP'd cast bullet is much better supported in the barrel and maintains it's balance much better and to a much higher acceleration rate

1. How is the PP supported much better than a cast bullet?

2. So, ballance is a key issue and a well cast, round bullet will be the same in that department as PP?

3. Explain the Acceleration issue, please and why PP is better at withstanding it.

4. Most PP bullets are cast bullets and some like Lyman are cast with grooves to hold the paper, what makes them able to do things that grooved bullets can't? Paper has no ridgity like jacketed bullets and the paper can can leave the surface of the bullet at different points in fight.

Frank

PS
Check out the 10 twist production class rifle accuracy in the CBA link

[frnkeore]

"That 323471 is a very well designed Loverin style bullet and one can push the RPM threshold upwards with it. I can push it also to 2150 fps with 2 moa accuracy and be right at the RPM threshold. It has one of the highest BCs for cast bullets that will shoot well at higher velocity and is a favorite of mine for longer range shooting (600 yards). However, if I back it off to 1850 fps it shoots 10 shot groups right at 1 moa at 100 and 200 yards out of my own 24/47."

Tell us why this multigroove bullet can be push faster than than the normal "threshold". I had figured that the PP got most of it's advantage from the lack of grooves. This bullet is is way above your threshold at 2150 in a 9.5 twist and should preform worse than say a 2 groove bore rider when compared to a PP.

Frank

[swheeler]

Nobade sounds like you have yourself a fine cast bullet launcher, have fun and enjoy and thanks for reporting.

[45 2.1]

I see this a lot here:
the issue of alloy and tensile strength is important
A cast boolit has NOTHING to do with tensile strength. A cast boolit is subjected to compression, shear and twisting. Those parameters involve compressive, shear and torsional strengths in a lead alloy...... not tension. Helps to know the actual psychical properties involved thru training and testing in a lab by people who teach these things, not reading out of a book yourself or guesstimating what happens.

[TXGunNut]

I'm just hanging around waiting for pics of Nobade's new rifle!

[swheeler]

I'm just hanging around waiting for pics of Nobade's new rifle!

+1 and a few pics of targets:)

[Nobade]

+1 and a few pics of targets:)

OK, as soon as I get some time to go out and play with it I'll get some pics. Had to work extra this week so the rifle is kind of lonely but soon I'll get it out to the range again.

-Nobade

[swheeler]

Watch out for a lonely rifle, she'll cheat on ya!;)

[RoyEllis]

Helps to know the actual psychical properties.....

Helps to spell properly so your argument isn't laughable at 1st glance. "psychical properties" is a rather poor malapropism for "physical properties". By the by, you may wish to read, reread and continue to read the 1st statement of your siggy until the irony of it all sinks in.

[Larry Gibson]

frnkeore

Obviously you're looking for another argument?

Won't get one from me but if your questions are sincere you could do simply as I stated and use the "search" function of this forum. Use "RPM threshold" as the key words and "Larry Gibson" as the poster. Check "any date" and then click on "search". You will find more than enough reading on the topic to answer your questions and keep you busy for a while.

For starters I'll help you out a bit and you might read this thread as it also answers your questions; http://castboolits.gunloads.com/showthread.php?123987-RPM-theshold-discussion&highlight=RPM+threshold

Larry Gibson

[frnkeore]

I am not looking to argue, I'm looking for facts.

Ok, after reading the above referenced thread, here is what I think about your threshold........... It's really not a threshold at all. You make exceptions to your own 120K - 140K rpm in many ways to make it still seem like it applies, such as the Loverin designs can push it up. The Loverin design by it's very design should push the threshold down, since it has lots of grooves, each one able to impart a imbalance, not only that but, the actual mold can cast out of round and can't be brought back to center by sizing.

The real limiting factor to velocity and twist is how well the load combination is assymbled and the harmomics it imparts on the barrel. With a well cast, round bullet assumed.

You've posted many times that the reason that someone isn't getting accuracy is because they've crossed your threshold when it could mearly be that the bullet is misaligned upon ignition and there can be many reasons for that. You also state that the powder speed effects your threshold considerably. If it is indeed a limiting factor in will have a real limit, not something that can be pushed around to fit your theory. Your limit is actually the misalignment and distortion associated with getting the bullet from the case into the barrel along with a lube that will keep it from damage as it travels through the barrel. PP is what does the latter best. I never PP because it wears the barrel. I shot PP slug guns for 3 years and that's why I know it occures and won't use them now, my barrels are dear to me.

If you want to shoot accurately at higer velocitys, you need a close fitting neck ,.0005 - .001 Max clearance in your chamber neck with your case neck to bullet fit. You need a freebore of about .1 -.2 (depending on number of bands) at .000 to no more than .001 over groove diameter and you need a long lead of .5 to 1 degree per side, plus a good lube for that purpose.

The reason that the 311299 shoots so well in milsurp and production rifles, is that the nose aligns itself to the bore and the large base bands fill the neck and throat fairly well, the only bad thing is that the steep throat angles and having to be swaged to .308 can cause distortion. The short Loverin (311465-6) shoot well in a 308 because the 308 has a freebore they can be fitted to and in the case of the 8mm, it has a very long lead (.43 deg) that can help align the 323470 & 471. The loverin has lots of lube but, you have to inspect the bullets carefully for flaws.

I do agree that you shouldn't spin them anymore than you have to, to minimize centrifical forces. I only shoot production (milsurp & production sporting) rifles for fun. I build and shoot my own match rifles for accuracy and match the bullet length and shape to the rifling twist. In 30 cal I use 12, 13 and 14 twist as I have no molds that need quicker twists but, as the results that I posted prove that you can shoot at 2000+ fps with a 10 twist and still get competitive accuracy, it disproves the "Thereshold" theory and shows that the bullet alignment, lube and fit have more to do with it than RPM. Competition is how you find limits and thoughs limits will alway be pushed in anyway the competitor can think of.

Attending and shooting in matches (especially CBA, ISSA & ASSRA) will enlighten you in many, many ways regarding BR accuracy.

Frank

[Larry Gibson]

Your limit

Frank

There in lays the problem with your analysis. The RPM threshold is not a "limit" at a specific RPM. It indeed can be pushed up or down with any given bullet of any reasonable fit. If it's not a factor then with all your experience at "The real limiting factor to velocity and twist is how well the load combination is assymbled (SP) and the harmomics (SP) it imparts on the barrel. With a well cast, round bullet assumed. perhaps you can enlighten us on how you shoot cast bullets accurately, out of say your 8x57 at 2400+ fps? How about the paltry '06 with a 170 - 180 gr cast at 2700 fps? You are correct in those things do have a bearing on pushing the RPM threshold upwards as does using a slower burning powder for the cartridge. There are other things involved like bullet design. The Loverins do so well because the most often have minimal noses and fit the case from base of the neck, the throat diameter and just bump the leade. They leave little room for unwanted obturation just as the Eagan designed bullet and the LBT designed bullets do.

Consider that Mr. Craig, with his heavy bench rest rifle very carefully made and with very precision reloading technique using the best of benchrest equipment of probably precisely cast and selected cast bullets managed to push the RPM threshold for a 10” twist rifle a whole 70 fps. Are you telling us, like a couple members and one former member, that joe average reloader/caster with his stock M1903 milsurp ’06, surplus cases and cast bullets from straight COWWs is going to even come close to pushing the RPM threshold at all let alone even 70 fps using “the load” of either Red Dot or 2400? O even with his M70, M700, Savage or other factory rifle?

I’ll refer you to post #1 in http://castboolits.gunloads.com/showthread.php?208186-RPM-Threshold-barrel-twist-velocity-chart. I explain all this again and include all that you mention is necessary. Perhaps if you want to reiterate 45 2.1s and his cohort, starmetal's arguments you should read all the threads and posts that come up in a “search”. I also suggest you go back and read my posts in the 1st suggested thread because they do answer all your questions and suppositions you have reiterated here.

Many here are very tired of the same old arguments proffered by a few against the RPM threshold. If you can shoot cast bullets accurately at high velocity then tell us how you do it and be prepared to prove it in front of reliable witnesses. Myself and bass ackwards worked diligently with a 311291 (not known for HV accuracy out of fast twist barrel) use my mould which I’m sure 45 2.1 will tell us all again how crappy it is. None the less both myself and bass were able, through proper loading techniques, to push the RPM threshold up over 2200 fps and maintain 2 moa or less accuracy from standard factory 30-06s with 10” twists so it can indeed be done. I have also pushed the RPM threshold with Lovern style (323471 in my own 8x57) and LBT bullets in the .308W and the .223 specifically and with other cartridges.

Consider this; if there was not a reason that regular cast bullets can’t be shot at the same high velocities as PP’d or jacketed bullets out of faster twist barrel they would be shot at the same high velocities. They would now wouldn’t they. Fact is they are not. There is a reason for it. A reason based on sound physics and ballistics, not conjecture.

It appears you have not read my answers or posts in the suggested thread. Had you actually read those you would have your answers. If you object to what I say then say so and prove otherwise instead of hypothesizing. Please don’t keep asking the same questions over and over as you have the answer to them from me. As they say, if you don’t like the answer don’t ask the question. That is, unless you are really just looking for another argument.

Larry Gibson

[swheeler]

Nobade good choice on the twist rate, enjoy!;)

[Larry Gibson]

Nobade good choice on the twist rate, enjoy!;)

Excellent subtle suggestion, let's keep the thread on topic.

Larry Gibson

[FAsmus]

Larry;

I will have to show my ignorance here, but so be it.

In this cast bullet game I've always heard the velocity itself was the limiting factor, not the RPM of the bullet. ~ Sure alloy, lube, hardness and bullet quality all enter in but the limiting factor always seemed to be bullet strength - or the inability of lead alloys to resist the heat and friction of the travel through the barrel after a certain velocity.

Please tell us, if you have the time, why jacketed bullets don't run into the same RPM limitation.

Good morning,
Forrest

[singleshot]

FAsmus,

Not being Larry, I'll still give the obvious answer. Jacketed bullets absolutely have an RPM limit. Here's a story to illustrate: I had a friend who was a competitive HP rifle shooter a handful of years ago who missed the Olympic Team by 2 slots. Anyway, he was manning the target pits one day, and another friend was on the line. As his friend shot, he could hear the sound of the bullet, then a very unfamiliar buzzing and whirring sound with each shot as the rounds travelled overhead. Lo and behold, none of the shots hit the target. Upon further investigation, they discovered that each bullet was breaking apart before it got to the target. His friend had been shooting his new fast-twist toy (don't remember specifics.) They realized the bullet was disassembling, not being able to withstand the RPM's they were pushed to. In the end, the friend had to swap in a slower twist barrel, and never had another problem. As stated before, this is simple physics and EVERY material has ultimate yield points where the material simply fails.

[Larry Gibson]

FAsmus,

Not being Larry, I'll still give the obvious answer. Jacketed bullets absolutely have an RPM limit.......

Single shot is correct. Not only do jacketed bullets have a "limit" when they spin apart but they also have a threshold where accuracy will deteriorate in a non-linear fashion.....just like cast bullets and PP'd for that matter. Jacketed bullets maintain their balance under acceleration much better than cast bullets. Thus the RPM threshold for jacketed is much higher, many time higher than the velocity attainable by the cartridge. Ever wonder why milsurp bullets aren't as accurate as commercial hunting bullets which many times aren't as accurate as match bullets? It's simply a matter of the jacket being concentric in thickness and form, the lead alloy being uniform in weight and swaged into the jacket with no air pockets of the commercial hunting and match bullets that make them more balanced in form (center of gravity/mass coinciding with center of form) that makes them more accurate.

Ran a test way back in the beginning of this RPM threshold discussion for bass ackwards to prove the point. I drilled a small hole in the side of some M118 match ammunition unbalancing them to a large degree so that the RPM threshold would be lower than the produced RPM. The test was conducted at 50 yards, 100 yards and 200 yards. 10 shots of unmodified M118 were shot at each range for group and 10 shots of the modified also for group. The groups with the unmodified M118 were consistent and exhibited linear expansion of group size between 50, 100 and 200 yards. The unmodified M118 group at 200 yards was just at 2 times the size of the 100 yard group just as it should have been. The modified M118 groups were larger and non-linear between 50, 100 and 200 yard groups. The modified M118 group at 200 yards was actually 3+ times larger than the 100 yard group. That is definitely non-linear and a sure sign the RPM threshold was crossed.

Velocity is not the limiting factor many think it is. Take cast bullets in 7, 9, 12 and 14" twist .223 Remingtons or 10, 12 and 14" twist .308Ws for example. Cast bullets can be driven to higher velocity in each with equal accuracy as the twist becomes slower. I can get 1 - 1.5 moa accuracy out of a 311466 consistently at 1900 - 2000 fps out of most any 10" twist .308W. I can get the same 1 - 1.5 moa consistent accuracy out of 12" twist .308Ws at 2200 - 2300+ fps. I can get the same 1 - 1.5 moa out of 14" twist .308Ws at 2600+ fps. Same bullet, same cartridge, same accuracy but different velocities. If you do the math though you'll find the RPM is close to the same for all velocities. Same holds true for the different twists with cast bullets in .223. It is the RPM.

Larry Gibson

[RoyEllis]

FAsmus,

Not being Larry, I'll still give the obvious answer. Jacketed bullets absolutely have an RPM limit...... They realized the bullet was disassembling, not being able to withstand the RPM's they were pushed to. In the end, the friend had to swap in a slower twist barrel, and never had another problem. As stated before, this is simple physics and EVERY material has ultimate yield points where the material simply fails.

I've personally seen and done this very thing with a 22/250 and thin jacketed varmint bullets...the spotter could see the puff as they blew apart in mid-air. So no matter what what claims the unwashed make, YES Virginia....there is a rpm threshold. It's not some arcane BS theory for Don Quixote's to tilt at but a simple law of physics. Every solid material known to man has a limit to stress induced by rotational forces, it isn't a "brick wall" type of thing as grain structure and molecular bonding of individual samples of 1 material can vary. BUT there is a range of stress that is the redline of impending stress failure. This is, I believe, what Larry has been so patiently attempting to explain even though some are he!!-bent on their own deviant troll agenda.

[felix]

Circumferential speed is dependent on the projectile's radius as we all know. Based upon that thought, is it the circumference speed or the functional radius (RPM) treated as the pivot for the accuracy limitation amongst the two parameters? I maintain it's the circumferential speed as the "real" limiting factor. But, for our argument they can be considered the same because of the dependency of all the factors we know about upon one another (incest, if you will). ... felix

[singleshot]

Circumferential speed is dependent on the projectile's radius as we all know. Based upon that thought, is it the circumference speed or the functional radius (RPM) treated as the pivot for the accuracy limitation amongst the two parameters? I maintain it's the circumferential speed as the "real" limiting factor. But, for our argument they can be considered the same because of the dependency of all the factors we know about upon one another (incest, if you will). ... felix

I agree. My own testing and experience indicate that smaller projectiles can be spun at higher RPMs and larger projectiles must have lower RPMs. Forces on the projectile are dependent upon the circumference of said projectile, simple physics.

[Green Lizzard]

nobade i wish all my 30s were 14 twist

[TXGunNut]

nobade i wish all my 30s were 14 twist

True That! Have a couple of pretty nice 1:10 30-06's that will probably never be uncased on a hunting trip or taken for a casual day at the range because keeping boolits under the threshold for these rifles simply doesn't interest me. They'll always shoot j-words and I'd rather shoot boolits. I have too many other rifles that I'd rather hunt or piddle with. Sad, very sad.

[Green Lizzard]

hey tx my 788 30-30 would work trying to get to 1850, real hard alloy maybe 2000 but my old 35 rem with 16 twist no problem even with 20 to 1 alloy

[TXGunNut]

hey tx my 788 30-30 would work trying to get to 1850, real hard alloy maybe 2000 but my old 35 rem with 16 twist no problem even with 20 to 1 alloy

Yes, my 35 Rem even seems to prefer softer boolits but I don't push it much over 2000 fps. She's headed to the range with me after another cup of coffee!

[Larry Gibson]

With a 16" twist 35 Rem one would have to use a very, very light weight cast bullet to even approach the RPM threshold. Doubt I could do it in my 26" barreled 35 Rem.....not enough case capacity and too small an expansion ratio.

Larry Gibson

[TXGunNut]

With a 16" twist 35 Rem one would have to use a very, very light weight cast bullet to even approach the RPM threshold. Doubt I could do it in my 26" barreled 35 Rem.....not enough case capacity and too small an expansion ratio.

Larry Gibson

It would seem to take a very fast load to cross that threshold but my 336 is happier with 190 gr boolits under 2100 fps for some reason. With the right powder I might be able to make it to 2200, just haven't seen the need. Still need to get off my **** and head for the range!

[Larry Gibson]

It would seem to take a very fast load to cross that threshold but my 336 is happier with 190 gr boolits under 2100 fps for some reason. With the right powder I might be able to make it to 2200, just haven't seen the need. Still need to get off my **** and head for the range!

My 35 Rem is also real "happy" with the 200 gr RCBS bullet at 2150 fps. That's as fast as it gets simply because that is at 100% load density with 4895. Suppose I could change powder but I haven't seen the need either. I do keep swearing I'll test that bullet with LeveRevolution powder just to see what it will do. However, I too must get off my **** and get to it......maybe one of these days.

Larry Gibson

[Green Lizzard]

thats the same bullet i use larry, i tell everyone that it was the easiest rifle i ever developed a cast load for. seemed that every thing i tried in it worked, but 4895 and 4759 stood out

[MBTcustom]

Not trying to tell anybody what's what, but some of this is very confusing to me. I know from my own knowledge of how things work, that any object has an RPM threshold, or point where it is no longer able to sustain itself in a balanced condition. Like spinning a top, the faster you go, there will be a point where the strain of inertia overcomes the gyroscopic effect that keeps it stable.
I also know that the point at which everything falls apart is greatly extended by the object being properly balanced.

The RPM theory holds that a cast boolit will no longer be able to keep itself together past about 140,000rpms (forgive me if that is wrong) because the alloy tries to sling itself apart in mid air which creates a compounding problem that deteriorates accuracy very quickly. (ie, once that boolit gets a little janky from the forces of inertia, it's all over but the cryin)

I would support that theory totally, because some of my own experience seems to back it up.
Unfortunately, (or perhaps fortunately) I have also seen evidence that suggests there is more to the story.
You might remember that the original reason I came here was to learn how to paper patch smokeless rifle boolits? I have seen the theoretical RPM threshold absolutely thrashed by paper patched boolits. This is common knowledge. One guy even pushed 180 grain cast boolits to 3000FPS with MOA accuracy in his 300winmag.
The point is, it's still a cast lead boolit of similar design, and of similar hardness, with the only change being the addition of a paper jacket (which, unlike a copper jacket, does nothing to improve the theoretical RPM limit of the cast lead boolit).
If the RPM theory is correct, why does a wisp of paper disprove it so consistently?

Again, I'm not saying that the RPM theory doesn't ever apply, but to use it to explain why a cast lead boolit bites it at about 140,000 to 160,000 seems like we may be in danger of glossing over a problem with an easy answer.

It reminds me of a story told to me by a professional forester a few months ago.
He told me that at one time it was commonly held that when pecan trees stopped producing, it was because they were lacking iron. To resupply the tree's with this "necessary" mineral, the owners were encouraged to pound a bunch of nails in the trunk of the tree, which would give it what it lacked. Sure enough, they would hammer nails into the tree and their superstition was reinforced with an abundant crop of pecans in short order.
It wasn't until many years later, with the help of science and good botany that it was discovered that the trees didn't need iron at all! By hammering in a bunch of nails, the tree was stressed, and it tried to reproduce it'self, thus bearing fruit.
The evidence consistently supported the belief, and there were folks that would get into all out table slapping arguments like we do on this issue.
Turns out, there were much less invasive ways to coax the trees into good harvest that didn't involve filling the trunk with nails, but it wasn't the folks with the hammer that discovered this, it was the scientists.

[Char-Gar]

I don't have a science bone or brain cell in my body, but always supposed that cast bullets are scored and have metal displaced by the rifling and this was a factor in the bullets losing accuracy after the bullet reached a certain RPM range. After the effect of rifling, the bullet is no longer round, but has a series of fins if you will to catch air as it whirls.

A cast paper patched bullet is not scored by the rifling. The paper takes that beating and the bullet exists the barrel round and without the fins to catch the air as it whirls.

I have always thought this was the reason a paper patched bullet can be fired faster which imparts more RMPs without having bad things happen to it. I have no reason to know this is true, but it just seem intuitive to me.

As an aside, Texans have long "thrashed" pecan trees to stress them and encourage the to produce more fruit. They usually do it with a long pole of some kind.

[MBTcustom]

I don't have a science bone or brain cell in my body, but always supposed that cast bullets are scored and have metal displaced by the rifling and this was a factor in the bullets losing accuracy after the bullet reached a certain RPM range. After the effect of rifling, the bullet is no longer round, but has a series of fins if you will to catch air as it whirls.


A cast paper patched bullet is not scored by the rifling. The paper takes that beating and the bullet exists the barrel round and without the fins to catch the air as it whirls.

I have always thought this was the reason a paper patched bullet can be fired faster which imparts more RMPs without having bad things happen to it. I have no reason to know this is true, but it just seem intuitive to me.

I'd be willing to go along with that char-gar, but that's not RPM getting you, that's boolit deformation. If that were the case, then why not shoot a barrel with polygonal rifling, and boost the RPM threshold to a more desirable level? That's not an RPM wall, that's boolit trouble.
Why would you drive down the freeway with flat tires, and blame the Chevy for being a lousy design, or say something like: "if I was driving a corvette, I could do 60MPH easily, but you can't expect that out of a pickup truck".
Why would anyone attribute a boolit problem to RPM? It just doesn't make sense.
Yeah, a Corvette will beat a pickup truck in a race, but what's that got to do with flat tires, and why would that ever be part of the discussion for your lousy gas mileage, or noisy ride to work?

[Dthunter]

Hello guys! Been working up a storm!
Looks like discussions got heated!

O well! All I know is that a rifle built with all of its components aligned and tight fitting is obviously going to have a better chance to shoot well. I have built barrels and custom rifles for a few years myself. And its fun as heck!

But as I have said all along, the limitation is our boolet alloy, and the physical forces imparted on it.

"One" of the reasons i feel the paper patch bullets fair better is that they leave the bore in the same condition "EXACTLY THE SAME" as they start. Provided the load/rifle doesnt cause the supported boolet to encounter an alloy "yielding" force. The paper supports suprisingly well!
A conventionally fired cast boolet has been directly engraved by the rifling and has some rifling grooves cut into it. This imparted "mechanical" aspect can cause issues to the integrity of the overall boolet. Just some food for thought.

[felix]

No seams on a baseball, no curve balls. Just that little disturbance on the ball causes hitters to go bananas. A ball with no spin will dart unpredictably upon any kind of non-uniform disturbance during its travel. Paper coatings rebound enough or just fly off and that eliminates enough of the rifling seams. Then the remaining boolit should be rotating enough to mimic the baseball fast ball. ... felix

[45 2.1]

All you guys who are say the PP boolit doesn't have rifling marks on it need to recover some of them. Unless it's steel it's going to have rifling engraved on it..... BTDT.................... however, you're free to believe anything else you want to.

[MBTcustom]

All you guys who are say the PP boolit doesn't have rifling marks on it need to recover some of them. Unless it's steel it's going to have rifling engraved on it..... BTDT.

Mine always had rifling marks on them. Not as defined as a standard GG boolit, but definitely visible.
However, I use green bar paper, and I have the boolits sized to the exact size that the paper would crush them if they were any bigger, so the patch bumps the groove into the underlying boolit fairly easily.
Perhaps paper is more accurate than steel?

[Char-Gar]

With many things it is a matter of degree. Hit yourself in the head with a six ounce hammer and then repeat with a three pound hammer. The depth of rifling marks on a bullet is markedly different between a paper patched and regular cast bullets.

[MBTcustom]

With many things it is a matter of degree. Hit yourself in the head with a six ounce hammer and then repeat with a three pound hammer. The depth of rifling marks on a bullet is markedly different between a paper patched and regular cast bullets.

OK, that hurt, and I don't feel any wiser. LOL!

I would have thought that the paper would have merely cushioned the boolit's transition from the case neck to the throat and lead of the rifling, allowing it to get there without being damaged by the misalignment of the two. I assumed that the paper acted like a shock absorber so that the boolit could "get religion" in the barrel with less damage.
However, I could be way off. I do believe this is the crux of the issue, but it's just a theory of mine. Someday, I'll have the equipment in place to really get a better idea of what happens to that boolit as it leaves the barrel. Until then, I'm just trying to find a possible solution that makes sense of all the evidence.

[Larry Gibson]

Goodsteel

The RPM theory holds that a cast boolit will no longer be able to keep itself together past about 140,000rpms (forgive me if that is wrong) because the alloy tries to sling itself apart in mid air which creates a compounding problem that deteriorates accuracy very quickly. (ie, once that boolit gets a little janky from the forces of inertia, it's all over but the cryin)

That is wrong. At no time have I ever said the RPM threshold caused bullets to come apart. There is a reason that some bullets will spin apart from too much RPM but that has nothing to do with the adverse affect on accuracy that exceeding the RPM threshold has. The RPM threshold also does not cause bullets to become unbalanced and lose their stability. The RPM threshold is when the unbalanced bullets centrifugal force is such that it causes the bullet to depart from it's line of departure/line of flight and go off on a tangent or go into a slow helical arc which radii increases non-linearly as the range increases around the line of flight. The bullet is most often still stable and flying point forward when the RPM threshold is exceeded.

You are correct about the unbalanced or damaged bullet being the problem. However, it is those unbalances and damage that the RPM act on while the bullet is in flight. The more unbalanced/damage and/or the higher the RPM the greater the inaccuracy will be. At some point of RPM the bullet will go off on the tangent or the slow helical arc.......that point is the RPM threshold. With regular cast bullets it is most often in the 120,000 - 140,000 RPM. With PP'd bullets (because they are less damaged/unbalanced) the RPM threshold is somewhat higher and with jacketed it is most always higher to the point of exceeding the velocity capability of the cartridge/rifle.

Larry Gibson

[MBTcustom]

Goodsteel

The RPM theory holds that a cast boolit will no longer be able to keep itself together past about 140,000rpms (forgive me if that is wrong) because the alloy tries to sling itself apart in mid air which creates a compounding problem that deteriorates accuracy very quickly. (ie, once that boolit gets a little janky from the forces of inertia, it's all over but the cryin)

That is wrong. At no time have I ever said the RPM threshold caused bullets to come apart. There is a reason that some bullets will spin apart from too much RPM but that has nothing to do with the adverse affect on accuracy that exceeding the RPM threshold has. The RPM threshold also does not cause bullets to become unbalanced and lose their stability. The RPM threshold is when the unbalanced bullets centrifugal force is such that it causes the bullet to depart from it's line of departure/line of flight and go off on a tangent or go into a slow helical arc which radii increases non-linearly as the range increases around the line of flight. The bullet is most often still stable and flying point forward when the RPM threshold is exceeded.

You are correct about the unbalanced or damaged bullet being the problem. However, it is those unbalances and damage that the RPM act on while the bullet is in flight. The more unbalanced/damage and/or the higher the RPM the greater the inaccuracy will be. At some point of RPM the bullet will go off on the tangent or the slow helical arc.......that point is the RPM threshold. With regular cast bullets it is most often in the 120,000 - 140,000 RPM. With PP'd bullets (because they are less damaged/unbalanced) the RPM threshold is somewhat higher and with jacketed it is most always higher to the point of exceeding the velocity capability of the cartridge/rifle.

Larry Gibson

I understand that, and I agree completely.
So, if it were possible to get the boolit started down the barrel undamaged, then it would probably emerge undamaged and have the same RPM potential that the paper patched boolit is capable of, right?
So the limiting factor is not the cast lead boolit, nor the RPM, but rather the reloader and the precision that he holds his loads to, and how well he assembles them and manipulates the components he has to get that boolit to work with the rifle instead of getting beat up by it, right?

[Larry Gibson]

goodsteel

So, if it were possible to get the boolit started down the barrel undamaged, then it would probably emerge undamaged and have the same RPM potential that the paper patched boolit is capable of, right?

That is correct. However, understand that you can get a perfectly concentric and balanced cast bullet (very difficult to come up with) started down the barrel undamaged but it can be heavily damaged during acceleration. It's why we must balance out the case capacity with a slow burning powder keeping the time/pressure curve as slow and low as possible to push the RPM threshold up.

So the limiting factor is not the cast lead boolit, nor the RPM, but rather the reloader and the precision that he holds his loads to, and how well he assembles them and manipulates the components he has to get that boolit to work with the rifle instead of getting beat up by it, right?

Yup, there in lays the "limit". As I've always said; the RPM threshold can be moved up or down depending on how well the bullets are cast of a correct alloy, the components used, and the skill with which they are assembled for the specific firearm. And if we do all correct and can push the RPM threshold high enough then we could run into the cast bullet exceeding the elastic/plastic capability of the alloy and potentially come apart.....but that's another story........

Larry Gibson

[MBTcustom]

Sounds reasonable!
I'm going to find a way to get you out here for a steak dinner one way or another!
I'm going to bust that RPM threshold, and then I'm going to take you out to my favorite shootin place. If that happens, bring a long range rifle. It's the closest thing to a wind tunnel you can get and still be outside.

[brotherdarrell]

I swore I would never get in the middle of this topic, but here it goes. Now I am not a wordsmith so I am just going to throw some things out to think about. How a person chooses to look at them will determine where they fall on this topic.

How fast can a cast boolit be spun and retain accuracy? Has that point ever been determined? I offer the following link as food for thought. Pay attention to posts #2 &#9 before coming to any conclusions.

(link didn't work. cut and pasted in next post)

The next comment is in reference to post #43. A jacketed boolit came apart when shot out of a fast twist barrel. The question is "why"? Was it:

a - the rmp threshold was reached for that bullet?
or
b - the rifling in the barrel compromised the integrity of the jacket allowing it to come apart under high rpm's.

If the answer is b then I have to point out that the CAUSE was NOT high rpm's. The cause was a compromised jacket. Kinda tips my hand, huh? If that very same bullet was placed in an accelerator sabot(assuming it was .22 cal) would it still come apart in a 1:10 twist '06? my bet is no.

I have been following these threads for the last couple of years and have read the threads from before that. There are those that say that rpm is the cause and those that say it is not. There is one common theme that all agree on if one takes the time to read what is actually written, and has been repeated on this thread. Goodsteel hit it on the head, Char-gar pointed it out, and Felix and, yes, even Larry.

The condition of the boolit after it leaves the barrel is THE determing factor as to the degree of accuracy at a given rpm. The first to effect this is the alloy and the last is the crown of the barrel. In between is a whole bunch of stuff like casting, sizing(did it go through the sizer straight?), seating in the case, chamber(is it straight?), fit in the throat (that is KING after all) and barrel condition just to name a few. As Larry pointed out in his last post rpm acts upon the imbalance in a boolit. This imbalance is THE CAUSE and the degree to which it is imbalanced determines where the rpm threshold is for a GIVEN boolit, chambering, load and rifle. That is why it is a threshold and not a limit.

When all the arguing and discussions are dissected it all comes down to one thing, is rpm THE CAUSE? All the other specifics most are in agreement with.

Do I think rpm is THE CAUSE? No, I think the relationship between rpm/twist rate/accuracy that Larry's data clearly shows is an indicator of everything that came before it. It can be a symptom of a problem in the loading/shooting sequence or it can be an indicator that you did something right.

For the record I would only state that I believe Larry's data in this field is good data. My experience and what others have posted only serves to back it up. I believe his methodology is good as it can be repeated and has been. I just disagree with his conclusion, as has been stated many times, that rpm is THE CAUSE. It is a major factor just not THE CAUSE. It's influence is determined by all that came before.

I also think that ultimately it comes down to terminology, semantics and a major case of which came first, the chicken or the egg. We know why rpm effects accuracy. I just think too much emphasis is placed on it. Work with what you got and control what you can control. If you have a 1:10" twist '06, well, deal with it.

Darrell - the preceding was my opinion and only that. If you disagree my feelings are not hurt.

oh yea, Nobade, if I was to build a cast boolit shooter it would be exactly like yours, twist rate included. Why fight a 1:10" twist when a 1:14" twist is much easier on the boolits?

[brotherdarrell]

My link did'nt work so I cut and pasted. Posts are by Bullshop in reference to cast and accelerators.

Post #2

Bullshop
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We have been messing with it some. Have done 30/30, 308 and 06, mostly 06. You will have to size the boolits to .224" but it has little to do with pressure. The problem with larger diameter is they do not consistantly release from the boolit. When running over size boolits we find the sabots anywear from just in fron of the bench to all the way through the target. When running .224" boolits all the sabots are about 30' in front of the bench. You dont need that seater tool if you have a lube sizer. All you need is a .308" die and a top punch that fits the boolit.
We are using a 55gn CBE boolit sized .224" without lube or gas check. We got a top velocity from the 06 of 4300 fps but about 3 moa. At 4000 fps we get about 1 moa.
Forget about the load data that comes with the sabots. All I can say is that it is safe, but I think they dont know people have chronographs now. To get the accuracy and velocity it takes powders considerably faster than anything you would use in those cartridges with normal weight bullets.
We started with the load data provided and worked each powder to the limit and ran out of room before we got real speed. We just kept going to a slightly faster powder and do the same thing each time until we finally got to the right burn rate that would give the velocity with normal pressure and good load dencity.
We are casting from straight WW but we are quenching for these kind of speeds. We have taken some small game with them and they do just what you would think a 55gn boolit would do at 4000 fps MV.
Hope that help ya a bit.
Blessings
BIC/BS

post #9

Here is some stuff I found,

4/28/07 45F
30/06
case - FC
bullet - 53gn CBE qww @ .224"
primer - WLR
powder - 52.5gn H4198
OAL - 2.896"
AMV - 3968 fps
ES - 16
test group @ 100 yards 5 shots @ - 1.046"

I have some recorded velocities for other powders but this was our bets load.

10/14/04 33F
30/30
case - RP
bullet - 22 Bator 6/1 WW/Monotype @ .224"
primer - CCI#250 LRM
powder - 38.2gn Scott 4197 (AA#2015)
no velocity listed
noted that this load shot to the same POI as 170gn 24gn 4197

12/5/06 20F
case - RP
bullet - 63gn RCBS
primer - RP#2 1/2
powder - 30.5gn H 4227
noted as good load, MAX

For seating depth it seemed more important to have the petals of the sabot about half covered by case neck than any relationship between sabot and rifling. Seating longer so the petals had no support had a negative affect on accuracy even though the sabot may in this way be in contact with the rifling the way you would expect with a boolit.
Some of these little details were important to good consistant accuracy.
With the 30/06 load listed we were getting better accuracy than from Rem factory sabot ammo at the same average velocity fired from the same rifle.
The load gave good average accuracy from three differant 30/06 rifles we tried it in.
Have fun and be careful. All the usual warnings do apply.
Blessings
BIC/BS

[35 shooter]

The rpm threshold seems to explain all the theories being put forth here the best. If there truly is no wall or threshold then why can't i shoot a 200 grain boolit in my whelen with 1/14" twist at 2900 fps with 1/2 min of angle @ 100 yards like i can regularly with hornady 200 grain jacketed?( I'm asking this seriously - trying to learn) After a lot of trial and error, the best i can come up with so far is just under or just over min. of angle anytime i get near or at 2400-2500fps. At about 2600 the best i've done so far is 2 1/2 groups and the same load may shoot 4" the next group. Also each different alloy from straight lead to heattreated ww will go increasingly faster with accuracy.
It does seem to be an rpm in relation to hardness which is affecting balance or something type of thing. Anyway i keep hitting a wall or threshold or whatever, that i can't seem to pass. All the alloys and loading tricks i've tried so far fall into Mr. Larry's theory but i'm new to cast in rifles so if there's a
way around the wall , i'd like to know what it is....Not arguing with anyone...just looking for answers. OK, just saw the above posts, must have come in while i was typing this out....that explains some of it.

[MBTcustom]

The rpm threshold seems to explain all the theories being put forth here the best. If there truly is no wall or threshold then why can't i shoot a 200 grain boolit in my whelen with 1/14" twist at 2900 fps with 1/2 min of angle @ 100 yards like i can regularly with hornady 200 grain jacketed?( I'm asking this seriously - trying to learn) After a lot of trial and error, the best i can come up with so far is just under or just over min. of angle anytime i get near or at 2400-2500fps. At about 2600 the best i've done so far is 2 1/2 groups and the same load may shoot 4" the next group. Also each different alloy from straight lead to heattreated ww will go increasingly faster with accuracy.
It does seem to be an rpm in relation to hardness which is affecting balance or something type of thing. Anyway i keep hitting a wall or threshold or whatever, that i can't seem to pass. All the alloys and loading tricks i've tried so far fall into Mr. Larry's theory but i'm new to cast in rifles so if there's a way around the wall , i'd like to know what it is....Not arguing with anyone...just looking for answers.

Well, just for the record, this is all just science and fun as far as I'm concerned. There really is no reason to get anywhere over 2000fps IIHO as long as you are deer hunting etc.
No reason in the world you need that much destruction and mayhem to be inflicted on your groceries! (see the link in my sig line).
I need a load that will kill deer like a champ, and I get that at 1800fps no problemo. However, the experimenter in me likes to know how fast, how long, how deep, how strong etc etc etc. Just like some people like to trick out a car to go faster than they would ever drive to work, I'm that way with boolits. Don't ask me why it's so deliciously invigorating! I don't have a clue! It's just something that I think about and enjoy (perhaps a little too much).

[35 shooter]

Well, just for the record, this is all just science and fun as far as I'm concerned. There really is no reason to get anywhere over 2000fps IIHO as long as you are deer hunting etc.
No reason in the world you need that much destruction and mayhem to be inflicted on your groceries! (see the link in my sig line).
I need a load that will kill deer like a champ, and I get that at 1800fps no problemo. However, the experimenter in me likes to know how fast, how long, how deep, how strong etc etc etc. Just like some people like to trick out a car to go faster than they would ever drive to work, I'm that way with boolits. Don't ask me why it's so deliciously invigorating! I don't have a clue! It's just something that I think about and enjoy (perhaps a little too much).

I saw those pic's when i joined up....awesome. That's the very reason i'm going in the morning with 1800fps. This will be my first season with cast in a rifle. I've done it before with a 44 pistol tho @ about 1100 fps. Put the smackdown on em for sure. Like you i like to experiment and the only way i know to learn is ask questions. This first year with the rifle has sure been a learning curve just working up loads...problem is i'm thinking that curve is just getting started good. Got a long way to go to catch up with you guys. Like i said..not arguing with anyone....learning!

[MBTcustom]

LOL! We're all just experts in training! You may think you have a long way to go, but you probably know more than me in one or two areas.

Remember: The most important questions you can ask are who, what, when where, why, and to what extent. Ask what do I see, but more importantly what don't I see. You're rifle is the best schoolmaster of all, and it never suffers from misinformation. It is always right, and will give you the answers you are after if you know how to learn from it.
Most folks (Often, myself included) listen to the boom sounds, and look at the holes, but that's all they manage to observe in the process of shooting.
I used to go out and just blast away buckets of WW metal and didn't learn a darn thing for it. These days, every shot is a plume of information that must be gathered and tried to be understood. There are many mysteries, but you have to pick something and tinker with it till you understand it, then pick something else. Divide and conquer.
Keep it up! The RPM debate has spurred many a booliteer to look closer, and try to understand what is happening.
It's kind of like a "if a tree falls in the woods and no one sees it" kind of a riddle in some ways. Kind of like the theory that "a perfect piece of glass is one of the strongest substances on earth" because glass must have a flaw to begin a crack, and theoretically, a perfect piece of glass will have no way to begin a crack, so it should be amazingly strong. Only problem is, there is no perfect piece of glass that can prove the theory! LOL!

[Char-Gar]

Well, just for the record, this is all just science and fun as far as I'm concerned. There really is no reason to get anywhere over 2000fps IIHO as long as you are deer hunting etc.
No reason in the world you need that much destruction and mayhem to be inflicted on your groceries! (see the link in my sig line).
I need a load that will kill deer like a champ, and I get that at 1800fps no problemo. However, the experimenter in me likes to know how fast, how long, how deep, how strong etc etc etc. Just like some people like to trick out a car to go faster than they would ever drive to work, I'm that way with boolits. Don't ask me why it's so deliciously invigorating! I don't have a clue! It's just something that I think about and enjoy (perhaps a little too much).

True dat!

[Larry Gibson]

brotherdarrell

This imbalance is THE CAUSE and the degree to which it is imbalanced determines where the rpm threshold is for a GIVEN boolit, chambering, load and rifle. That is why it is a threshold and not a limit.

That is basically it. However if there is no imbalance there is no threshold. Imbalance is still not the root cause nor is RPM. The root cause is the centrifugal force. If there were no centrifugal force even the imbalanced bullet would shoot accurately and the bullet with the damaged jacket would not spin apart regardless of the how high the RPM was.

Also keep in mind that centrifugal force has it's effect on the bullets accuracy only in the exterior phase of ballistics (flight). Thus the only way to keep the centrifugal force low and reduce it's adverse effect on accuracy is to reduce the RPM through lower velocity or a slower twist with a given velocity.

All the quality machining, blueprinting, casting of perfect bullets and excellent benchrest loading techniques can do absolutely nothing to affect centrifugal force. They only affect how much imbalance is in the bullet on exit from the barrel. The centrifugal force from whatever level of RPM is present then has an adverse effect on the imbalances, if any, of that bullet causing some level of inaccuracy.

Even before the RPM threshold is reached all bullets are adversely effected accuracy wise from centrifugal force. The effect of centrifugal force on any imbalance causes the bullets center of spin not to coincide with the center of mass or with the center of form. It's why guns shoot groups, even those of the highest accuracy potential from machine rests. There is a good explanation of this in Hornady's Manual with pictures even.

Larry Gibson

[GabbyM]

What interest me is to see if the 1:14" twist rate will keep a bullet like 200 grain Lyman #311299 stable out to five or six hundred yards.

[MBTcustom]

Also keep in mind that centrifugal force has it's effect on the bullets accuracy only in the exterior phase of ballistics (flight). Thus the only way to keep the centrifugal force low and reduce it's adverse effect on accuracy is to reduce the RPM through lower velocity or a slower twist with a given velocity.

All the quality machining, blueprinting, casting of perfect bullets and excellent benchrest loading techniques can do absolutely nothing to affect centrifugal force. They only affect how much imbalance is in the bullet on exit from the barrel. The centrifugal force from whatever level of RPM is present then has an adverse effect on the imbalances, if any, of that bullet causing some level of inaccuracy.

Larry Gibson

I don't know about that Larry. Just from what I have seen in my short legged experience leads me to believe that most factory rifles have very specific problems built into them as safety measures, and as inconsequential defects. These things make it nearly impossible to get a concentric boolit past the crown of the rifle. These things are also very fixable, if you know how.
Now, how much effect does the correction of these defects have on the boolit and the RPM limit of them? I'm still figuring that out, but I'm hoping it's dramatic.

For instance, do you think it's really RPM that's getting you, or the damage that naturally happens when you slam a soft boolit into fast twist rifling?
Why is it that a powder with a gentler energy profile seems to give better accuracy from cast boolits?
Could it be that it allows the boolit to get started engraving better before it really gets the kick in the pants?
Could it be that the very fact that faster twist rifling has a more aggressive engraving characteristics is the real reason the RPM appears to be a limiter?
Have we just been hammering nails into trees?

[felix]

Tim, what you have said is indeed correct. All of it. The RPM rule is just a composite method of advance REPORTING of the projectile's problem, not the problem itself. Damage done to the projectile is due to the act of acceleration, or externally by the forces within the projectile afterwards. ... felix

[singleshot]

So, what we all need is smooth bore guns and stabilizers on the projectile like the M1 tank. That will solve all our problems, no? :-)

[Char-Gar]

I have pretty well convinced myself that how fast you accelerate the bullets will have a big impact on it's accuracy. That is why accuracy starts to go south with fast powders like 2400 when you get past 1.8K fps or so. The alloy will make a difference.

Contrast that will very slow powders like WC872 that push the bullet out of the barrel with less damage due to slow progressive acceleration. Fine accuracy can be had at higher than that obtainable with 2400 or like powders. Again, the alloy will make a difference.

I think the RPM thing has something going for it. But it is just one of the factors that limit accuracy at higher velocities. Very few things in life are "either or", most are "both and".

1. RPMs imparted
2. Temper of the metal
3. Depth of rifling engraving on bullet
4. Speed of powder
5. Design of the bullet
6. Probably a bunch of other factors as well.

[Larry Gibson]

For instance, do you think it's really RPM that's getting you, or the damage that naturally happens when you slam a soft boolit into fast twist rifling?

Goodsteel

To arrive at the correct answer you must separate the two distinct parts of ballistics which you and many others lump into one. There is "internal ballistics" which is what happens to the bullet in the barrel during ignition, acceleration and exit from the barrel. This is where you are mainly focused. As mentioned before; you can have a perfectly cast and loaded concentric and balanced bullet in a cartridge loaded into as close to perfect rifle as possible and yet it can be sufficiently damaged during the internal ballistic phase to cause some degree of inaccuracy.

In the other ballistic phase called "external ballistics" from the bullets exit of the barrel to target impact is where the centrifugal force comes into play acting upon those imbalances in the bullet. As we can see the external ballistic phase is completely different. For a given cast bullet at a given RPM the centrifugal force will be there and there is nothing that a perfectly made rifle can do about it or change it. However, as mentioned the more balanced we can launch the bullet the less imbalance that centrifugal force has to act upon.

In all my pressure testing of equal loads in different twist 223s and .308Ws I have yet to see real evidence (velocity variation, psi variation or any difference in the time/pressure curves) that a cast bullet is "slammed" into a fast twist barrel any "harder" that a slow twist barrel. The bullet is fully engraved and spinning at the rate of the twist at one bearing surface of bullet travel. That happens very early in the time/pressure curve well before the peak psi is reached and well before the full velocity is reached (at the muzzle). Bullets slamming into the fast twist rifling harder sounds good in theory but I've found no proof of it in closed breach rifles.

Why is it that a powder with a gentler energy profile seems to give better accuracy from cast boolits?

Because the slower time/pressure curve causes less obturation, slumping and/or collapsing of the bullet. Thus it causes less damage and imbalance to the bullet. Take an ingot of lead and push it across the bench 26" with a hammer. Then smack it the same 26" across the floor in one whack with the hammer.....see the damage difference to the ingot.....same principle applies. A softer slower time pressure curve will always cause less damage to the cast bullet during acceleration than a faster burning powder even though both may hit the same peak psi. BTW; even given the same peak psi the slower time/pressure curve will also produce the higher velocity.

Could it be that the very fact that faster twist rifling has a more aggressive engraving characteristics is the real reason the RPM appears to be a limiter?

As already discussed; nice in theory but it doesn't prove out........If it were the case then the slower twist barrels would maintain accuracy at a higher RPM since the bullets didn't "slam" into the rifling as hard and were thus less damaged/imbalanced. But they don't, accuracy in the slower twist barrels goes south at the same or even a bit lower RPM than in the faster twist barrels. Yes the velocity is higher in the slower twist barrels but the accuracy loss at pretty much the same RPM. That is the proof.

Have we just been hammering nails into trees?

Probably, at least until we separate internal ballistics from external ballistics and understand the causes and effects during both. BTW; there are 3 spate phases of ballistics; internal, external and terminal ballistics. All 3 are separate and have different physical forces affecting them. That is why when we combine 2 of them we can just be hammering nails into trees...........

Larry Gibson

[Larry Gibson]

Additionally

By all means do make the rifles as precise as possible because that is one way we lesson the potential for imparting additional imbalances to cast bullets and to raise the RPM threshold. However, if we are dealing with a factory rifle, be it commercial or milsurp, then it is what it is and we must expect a probable lower RPM threshold all other things being equal.

Larry Gibson

[felix]

Smooth bore guns work fine indeed when the projectile is guided externally. ... felix

[nanuk]

sometimes I have flashes back to some reading I did in another lifetime

this one was about a boolit with a hollow core, and how that would affect the RPM threshold....

but for the life of me, I can't remember where I read it....

[frnkeore]

This is my problem with Larry's "threshold". I've seen numerous posts by him stating that people that are having trouble with accuracy at 1800+ fps in a 10 twist won't be able to get it because they in this "threshold", rather than helping them obtain good casting or loading technics to further accuracy or that someone won't be able to attain accuracy if they want to shoot there 10 twist at 2000+ fps.

I say if this "threshold" isn't a limit, what is it's purpose and why so many posts about loosing accuracy because of it? If someone has exceeded the "threshold" with accuracy, it's, well it's only a "threshold" and not a limit. A threshold is a entry way and if you go through a threshold, you enter something different, in this case it's assumed by almost anyone (yes, that's the way it's always presented) that you enter a area with LESS accuracy. If you can completely cross it with better accuracy than 90% of target shooters, there is something wrong. With more confidence, I will say that this "threshold" starts at the minimum rpm that any bullet will stabilize gets better and worse throught it's travel down the barrel and out to the target.

Something that I find has been neglected in this discussion is heat. The heat of the propellant burning, the heat of pressure (2 deg per lb of compression), the heat of friction in the barrel and the heat of the bullet in supersonic flight.

I seen no evidence of scientific testing, such as a blind test (an objective shooter not involved in the theroy) , using one action and several barrel twists, barrels of the same length and conuture, chambered with the same reamer. And then there are so many bullets lengths, bullet types, nose shapes, primer and powders to consider, also. Another thing that you will find in doing as suggested is "nods" of accuracy that have to be evaluated and seperated from the RPM data.

I also agree with Felix regarding smaller calibers and the effect of distance of the imbalance from the center of mass.

Frank

[MBTcustom]

I realize that each ballistic condition should be considered separately.
However, I would pose you the question of which has the most effect on a boolit performance?
The way I see it, the further away from the primer you get, the less effect a variance is going to have on a boolit's flight. Personally, I think the lions share of the problems are happening in the chamber of the rifle itself. The external ballistics are merely a way of measuring your proficiency at dealing with internal ballistics.
I also hold that a copper or paper jacket is just a way to glaze over problems with lousy internal ballistics. It gives the boolit a cushion and allows you to get away with normal reloading techniques, that depend on crutches like copper jackets to get around certain things that are too much of a pain to compensate for if you want your ammo to be used in any chamber.
The thing is, we're not just shooters we're handloaders. We are in the business of customizing ammo to our specific guns, so why not take it all the way?
Why not make everything fit correctly, and why explain away lousy high-speed groups with external ballistics, when we are in the business of controlling external ballistics with internal ballistics? One effects the other to a lesser degree as you go on down the line to the end result of terminal ballistics.
I don't see why we would suggest that external ballistics controls something that is behind it in the order of progression.
If a theory were to be made, it seems that it would be far more logical to suggest that perfect internal ballistics would result in perfect external ballistics etc etc etc.
I demand logic dad burn it! LOL!

[Love Life]

I wonder, I wonder....

As I sit hear reading this many things come to mind. Some say there is a RPM thresh old and others say the boolits shred due to some issue with poor rifle build, poor bore, etc.

An experiment is in order. If indeed an RPM thresh hold exists, period, is it safe to assume that a 40 gr bullet hammered down a 1 in 7.5 twist 243 would vaporize? Would that not show that RPM can indeed shred a bullet? Assuming the rifle is up to snuff of course...

A little more thought here. So, if a rifle were perfect in all aspects, would a RPM thresh hold not exist?

Those seem to be the 2 lines of thought here.

A) A RPM thresh hold does exist
B) A RPM thresh hold does not exist. The boolit/bullet shreds due to alignment issues, bad bore, poor casting, etc.

What if you swaged lead rifle projectiles? Wouldn't that alleviate the poor casting issues?

[MBTcustom]

Love life, not really true.
We all agree that the RPM threshold exists. Some of us disagree with the assertion that it is the reason accuracy falls apart above a certain RPM that is drastically lower than similar boolits that are gift wrapped.
Personally, I really want to buy Larry a steak dinner, and he made the mistake of promising that he would come out here to witness my success (thereby giving me the opportunity to do so) if I am able to successfully prove my point.
I've been thinking about it though, and I think it would be better if I went out to see him instead. (the fact that he has an Ohler shooting lab never entered my mind[smilie=1:)
Course, I've got the little problem of getting a rifle to shoot first, but I shan't be bothered with details! LOL!

[Char-Gar]

I do know I have a Marlin 336A in 30-30 that will shot a 170 grain FNGC bullet at an honest 2,100+ fps over a stout charge of 3031 powder and will deliver great accuracy. Dropping the velocity to 1.7K fps does not improve accuracy. The rifle has a 1-10 barrel. So the RPM threshold does have some slip and slide in it.

[brotherdarrell]

Larry - you state that the centrifugal force causes the unbalanced boolit to veer off. I say the imbalance in the boolit allows the centrifugal force to act upon it. In short we are saying the same thing. Again it comes down to semantics, terminology and which came first the chicken or the egg. In the end everything else all are pretty much in agreement with.

One last thing and I will lay this to rest. If rpm was such a limiting factor how is it that Bullshop was able to shoot a lead alloy 22 cal boolit at 4,000 fps in a 1:10" twist and maintain close to moa accuracy? And what is the rpm of said boolit? I do know he didn't do it by limiting the rpm.

Respectfully

Darrell

[MBTcustom]

I do know I have a Marlin 336A in 30-30 that will shot a 170 grain FNGC bullet at an honest 2,100+ fps over a stout charge of 3031 powder and will deliver great accuracy. Dropping the velocity to 1.7K fps does not improve accuracy. The rifle has a 1-10 barrel. So the RPM threshold does have some slip and slide in it.

Actually char, your all over it like a cheap suit. 2100 out of a 1-10 puts you at about 150,000rpm. Right where Larry says you aught to be (140,000 - 160,000rpm).

[Nobade]

OK, I made it out to the range today with some different ammo. RCBS 165SIL, wheelweight metal water quenched, lubed with 50/50 alox/beeswax. Load was 44gr. IMR4895 since that worked well the last time with the Ranch Dog boolits. First shot at paper at 100M, decent but not amazing. Right at 1MOA, with most of it being vertical. Took my last ten rounds, spent two getting a zero, and shot the last 8 at the 500M hanging steel. Right at a 6 inch group in the middle of the plate. (the three outliers were already there, I swear!) Not going to set the world on fire but certainly respectable I believe for naked cast boolits at somewhere between 2400 and 2500 fps.

8720987210

-Nobade

[MBTcustom]

Larry - you state that the centrifugal force causes the unbalanced boolit to veer off. I say the imbalance in the boolit allows the centrifugal force to act upon it. In short we are saying the same thing. Again it comes down to semantics, terminology and which came first the chicken or the egg. In the end everything else all are pretty much in agreement with.

One last thing and I will lay this to rest. If rpm was such a limiting factor how is it that Bullshop was able to shoot a lead alloy 22 cal boolit at 4,000 fps in a 1:10" twist and maintain close to moa accuracy? And what is the rpm of said boolit? I do know he didn't do it by limiting the rpm.

Respectfully

Darrell

Bullshop isn't the only one who has done that. You do some digging and you run a cross lots of members that have accomplished this feat.

Darn nice looking rifle you got there Nobade! Good shooting too!

[brotherdarrell]

Goodsteel - not sure you saw that correctly. That was a 22 cal cast boolit at 4,000 fps, not 3,000 fps. I have done a lot of digging and the closest I have seen was Bullshop, again, with a 221 fireball around 3400 fps, and that was not with a 1:10" and it was not moa(if I remember correctly). It is petty darn good, though, and better than I have done.;)

Darrell

[Larry Gibson]

frnkeore

I say if this "threshold" isn't a limit, what is it's purpose and why so many posts about loosing accuracy because of it? If someone has exceeded the "threshold" with accuracy, it's, well it's only a "threshold" and not a limit. A threshold is a entry way and if you go through a threshold, you enter something different, in this case it's assumed by almost anyone (yes, that's the way it's always presented) that you enter a area with LESS accuracy.

Right idea but convoluted. The threshold is not a limit as a limit is set. A threshold, in this case the RPM threshold, is not set as such. I have said many, many times and explain it in the thread I advised you to read that the RPM threshold can be moved up or down. With a given rifle and given components once you cross the threshold inaccuracy is the result. char-gar's claim with his 10" twist 30-30 is just above the general range of the RPM threshold I have stated over and over. He has pushed the RPM threshold up with his rifle and components. I bet if he used everything the same except the powder and used 2400 instead he would not get the same accuracy at 2100 fps.

Larry Gibson

[Larry Gibson]

Love life

A little more thought here. So, if a rifle were perfect in all aspects, would a RPM thresh hold not exist?

You can easily have the perfect rifle (well if you can afford it) but the trick is also to cast perfect bullets, load them perfectly and accelerate them w/o unbalancing/damaging them. IF you can do that so the cast bullets are then perfectly balanced in flight with the center of mass (form), center of gravity and the center spin all perfectly coinciding there would be no RPM threshold. Reason being the centrifugal force would be affecting the bullets equally in all directions.

Do we see where the trick to this lays?

Larry Gibson

[35 shooter]

That's good shooting Nobade! Looks like you and that rifle were made for each other. Congratulations on a fine shooting rig. Looks good too.

[Love Life]

What about swaged lead boolits? Wouldn't they be more balanced than a cast boolit? Would swaged lead boolits have a higher thresh hold?

I see where the trick lays. Many layers to this onion here and it makes for great reading.

[frnkeore]

Larry,
If your "threshold" can be pushed both up and down, why is it valid? Why not just say that you may have throuble getting accuracy above a certain RPM if, your casting, loading and rifle build aren't at a optimum. You could also add that the absolute max. RPM is X and X can not be exceeded with accuracy.

You also need to define that accuracy in MOA if you like but, it does need to be defined. 4 MOA @ 100 is fine for taking deer at that range but, 1 MOA @ 100 won't win a cast bullet match.

Frank

[Larry Gibson]

brotherdarrell

One last thing and I will lay this to rest. If rpm was such a limiting factor how is it that Bullshop was able to shoot a lead alloy 22 cal boolit at 4,000 fps in a 1:10" twist and maintain close to moa accuracy?

Bullshop did that by using a sabot. The bullet was held in place and not allowed to be damaged during acceleration by the sabot. Same as with a jacketed bullet with a lead core. Same as Hornady standard 55 gr SPs can be driven to 4000 fps out of 14" twist barrels but the very same designed Hornady 55 gr SX with a thinner jacket will spin apart at 3600 or so fps. Same reason Siearra Blitz bullets can be spun apart.....same reason Hornady and Sierra caution not to use those bullets above 2700 - 2800 fps in fast twist barreled .223s as they will spin apart.

Unbalance bullshops saboted bullet and you will see the effects of RPM at that velocity. Same as I unbalanced M118 bullets for bass ackwards when I ran the test for him. The RPM threshold is real, many here and other cast bullet shooters have run into it for years....ever sind GC'd cast bullets have been in use actually.

Larry Gibson

[Larry Gibson]

Larry,
If your "threshold" can be pushed both up and down, why is it valid? Why not just say that you may have throuble getting accuracy above a certain RPM if, your casting, loading and rifle build aren't at a optimum. You could also add that the absolute max. RPM is X and X can not be exceeded with accuracy.

You also need to define that accuracy in MOA if you like but, it does need to be defined. 4 MOA @ 100 is fine for taking deer at that range but, 1 MOA @ 100 won't win a cast bullet match.

Frank

frank

Not my "theory". As I've stated before I picked up on some time back from a gun magazine. If I had the magazine and article I give it to you. I read about the theory many years ago, probably back in the '80s and have been proving it's existence ever since. Many others have proved it's existence also, just read the posts in this thread.

I don't need to define accuracy as a given moa. Reason being is the accuracy in moa has nothing to do with the RPM threshold. If your rifle is capable of 3 moa and your load crosses the RPM threshold then accuracy will get worse. If your rifle is capable of 1/2 moa accuracy and your load crosses it's RPM threshold the accuracy will get worse. Accuracy for both will also get worse as the range increases because the group dispersion (the measure of accuracy) will increase in a non-linear fashion.

If you are only shooting deer out to 100 yards and that 4 moa load at 100 yards is exceeding the RPM threshold then it won't really matter as you should kill all the deer you want. However, if that 4 moa load at 100 yards has exceeded the RPM threshold it may very well be giving 12 - 15" groups at 200 yards. So if your hunting deer to 200 yards you may very well miss the deer as the range increases due to the non-linear expansion of the cone of fire (group capability, i.e. accuracy)

As to winning matches having studied the CBA match results for many years we can just about count on one hand the number of "winners" who's loads pushed the RPM threshold. Then as with Mr. Craig's winning load you posted, the RPM threshold was not pushed up by very much.

Larry Gibson

[Larry Gibson]

Nobade

That was outstanding and verifies exactly what we are talking about. Nice group BTW.

Larry Gibson

[brotherdarrell]

Larry - based on your answer we agree 99.9%:lol:

Darrell

[MBTcustom]

Larry,
I can't see an issue either because you are saying that the rpm depends completely on the internal ballistics of the rifle (which is a very sound scientific argument) and thus, could be anything depending on the perfection of the exiting boolit.
I was under the impression, from reading your writings, that you have not always held this to be true, and even made an offer at one point to travel to meet the booliteer that could shoot a cast lead boolit over a certain RPM. I confess, this got my attention.
But, if you no longer believe that a cast lead boolit is held by any rpm boundaries, then I suppose I'll have to eat the steaks myself.
There seems to be subtle difference in the way you have presented the rpm theory in this thread as opposed to another?

So what's all the hubbub about? The rpm theory boils down to: "It only shoots if it does"?
Furthermore, it could be any combination of external ballistics that acts on the imbalances in an imperfectly launched boolit. Why drive a stake in the ground with RPM? Shoot the same boolit in a vacuum with no friction from the air, and no gravity to contend with, and I doubt it would be as limited there either, because those forces work in tandem with rpm to jack with the projectile.
Now, it's true that rpm is the only one of those three measurable forces that we have any control over, and certainly, the case could be made that it carries the lions share of the variable because it is also not as consistent as the other two (or any of the other forces that effect external ballistics) but to make the jump that it has anything to do with something behind the crown of the rifle is bass-ackards.
Just because we have control over it, and it has effect on what's coming out of the barrel, doesn't mean it's effect is supreme. The RPM's leash is held by internal ballistics, not the other way around.

[LynC2]

I don't know about that Larry. Just from what I have seen in my short legged experience leads me to believe that most factory rifles have very specific problems built into them as safety measures, and as inconsequential defects. These things make it nearly impossible to get a concentric boolit past the crown of the rifle. These things are also very fixable, if you know how.
Now, how much effect does the correction of these defects have on the boolit and the RPM limit of them? I'm still figuring that out, but I'm hoping it's dramatic.

For instance, do you think it's really RPM that's getting you, or the damage that naturally happens when you slam a soft boolit into fast twist rifling?
Why is it that a powder with a gentler energy profile seems to give better accuracy from cast boolits?
Could it be that it allows the boolit to get started engraving better before it really gets the kick in the pants?
Could it be that the very fact that faster twist rifling has a more aggressive engraving characteristics is the real reason the RPM appears to be a limiter?
Have we just been hammering nails into trees?

I was wondering the very same thing. Last Saturday we had a lever action match at the local gun club and Nobade and I were discussing various subjects on cast boolits and different calibers. The subject of the cruise missile in the 6.5 Swede came up. He said he would often get two strikes per shot on a target during his early testing and theorized that the boolit was twisting in half. (Pretty logical, right? ;) ) Anyway after he paper patched them the problem went away and he was able to load them fast enough for the rifle to shoot to the issue sights. To me, that sounds like the alloy wasn't strong enough to resist the torsional forces acting upon it due to the abrupt start once the boolit engaged the rifling.
I may be way off base here, but perhaps the paper patch eased the transition of the boolit's spin from 0 to high RPM since the patch engraved the nose part early in its journey down the bore?
It also makes me wonder if one had a pre engraved boolit (like the false muzzle used in some muzzle loaders or like the Whitworth) if that would alleviate the issue.
If nothing else is accomplished, this thread has created some very interesting and lively discussion on the subject that makes one realize there are a lot of variables and unknowns in our hobby.

[swheeler]

Nobade you've got yourself one fine rifle there, nice shootin at 500M too.

[Larry Gibson]

Goodsteel

I was under the impression, from reading your writings, that you have not always held this to be true, and even made an offer at one point to travel to meet the booliteer that could shoot a cast lead boolit over a certain RPM. I confess, this got my attention.
But, if you no longer believe that a cast lead boolit is held by any rpm boundaries, then I suppose I'll have to eat the steaks myself.
There seems to be subtle difference in the way you have presented the rpm theory in this thread as opposed to another?

Obviously you've been talking to a former banned member?

No, I have always held the damage/unbalancing to the bullet occurring during casting, loading and acceleration was what the centrifugal force acted upon during flight. That is what happens.

Yes I did make an offer at one point to travel to meet the booliteer that could shoot a cast lead boolit over a certain RPM as did several others here. The reason was not one of doubt regarding the RPM threshold because I do not doubt it. The reason for the offer was because I, and the others who made the same offer, did not believe the BS that "booliteer" was claiming and asked that he prove his HV high RPM accuracy claims in front of us. He refused to prove his claim in front of reliable witnesses as has his cohort. They were given the benefit of doubt however as if you read my 6.5 Swede thread you will see how I went to every length possible to follow their directions and did not equal their accuracy claims at the HV/RPM they claimed. No one else has consistently (one group, especially a 3 or 5 round, does not equal consistent accuracy) equaled their claims either. I, after doing everything they said, only succeeded in pushing the RPM threshold up a bit. I even used the same bullets as sent to me by one of them.

You live closer to both of them than I, perhaps they will demonstrate consistent HV, high RPM with accuracy to you with regular cast bullets as they have claimed?

BTW; just this last week I finally got around to some preliminary testing with the CM in my 6.5 Swede using RL22. Accuracy (M38 "scout" with 2X Leupold scout scope) at 100 yards held very good at a consistent 1.5 moa until the velocity hit just at 1700 fps. That is just a bit above the RPM threshold figure of 140,000 RPM and accuracy held because I pushed the threshold by using bullets that had a very good fit in the throat, because of the slow burning RL22's time pressure curve and because the cases fit the chamber. At 1800 fps accuracy started going south with one uncalled flyer. Then accuracy really went south as velocity/RPM went above that. Keyholing started at 1950 fps. At 2019 fps the keyholing group was 12" so I moved the 21" x 24" target in to 50 yards. Subsequent test loads up through 2500 fps (Oehler M35P with center screen 15' from muzzle) produced only 1 -3 hits on that target. None of the hits, though keyholed, showed evidence the cast CM bullets had broke in two. The CM bullets were cast in one of the oversize moulds and are to oversized to seat properly w/o the GC and bottom 2+ driving bands being down inside the case. The CMs were cast of 80/20 linotype/ lead and AC'd. Once age hardened the nose was uniformed in a .264 die, 1st two driving bands in a .266 H die and the main driving bands and GC at .268. Hornady GCs are used and CR is the lube. This sizing allowed the bullet to chamber with the top of the GC staying at the bottom of the case neck. In other words the CMs were sized to fit the rifle's throat. As we see, once again the RPM threshold was pushed a little up but it was still there and I crossed it right about 1800 fps at about 155,000 - 160,000 RPM.....


Keep that money in your wallet for the steak dinner, I will collect on it.

Larry Gibson

[Char-Gar]

Goodsteel...This RPM discussion has been going on for a very long time with a number of people involved. It has often become acrimonious in the extreme. Problems happen when folks take the position that they absolutely and totally have it figured out and others that are no so certain about the conclusion question their conclusions or at least express doubt. When this happens, positions are staked out, lines drawn in the sand and the game is afoot.

Those of us who have been at this thing for a while, knows what works (for us) and what does not. When somebody comes along and says; "I can do it better than you because I know more than your do", then we have a real problem. Folks just don't seem to be able to relate their experience and their opinions and let it go at that. They must defend their opinion as absolute truth and take on all who would dissent.

Discussion and debate often produce light but all to often it just produced heat. Folks need to know when to just let it go and walk away.

[45 2.1]

Goodsteel...This RPM discussion has been going on for a very long time with a number of people involved. It has often become acrimonious in the extreme. Problems happen when folks take the position that they absolutely and totally have it figured out Seems this could very well apply to the RPM theory declaration.and others that are no so certain about the conclusion question their conclusions or at least express doubt. When this happens, positions are staked out, lines drawn in the sand and the game is afoot. I have said repeatedly that you can shoot normal 10 twist barrels accurately at high velocity (and have better accuracy than what the RPM promoter has given). I did not say it was the only way.

Those of us who have been at this thing for a while, knows what works (for us) and what does not. When somebody comes along and says; "I can do it better than you because I know more than your do", then we have a real problem. That's no different than doing something in the real world (not cyber space), people do not have equal skills.... some do better than others. That is what the bell shaped curve is about.Folks just don't seem to be able to relate their experience and their opinions and let it go at that. They must defend their opinion as absolute truth and take on all who would dissent. And you do this also on quite a few topics.

Discussion and debate often produce light but all to often it just produced heat. Folks need to know when to just let it go and walk away. I did, but some others keep posting on it... effusely.

This would be a good spot to tell the folks what happens when you shoot a 180 gr. boolit (or the very popular 311284/311299/314299) in a 14 twist..... either 308 or 30-06 users are welcome to explain. Those light boolits you're bragging about don't carry well at really long distances (500 yards and over for cast) in a 14 twist. Tell us how well or not they shoot. Of course, if no one speaks up, then we can surmise they know it doesn't shoot too well.

[Larry Gibson]

Goodsteel

Nobade has made the point with his 14" twist rifle. You have the ability and expertise to find out for yourself. Perhaps a good action and 3 identical barrels 26" long with 10, 12 & 14" twists chambered for the 30x57 and a good cast bullet such as the 311466 or the LBT 150 gr would give you the better answer.

As for me any member of this forum is more than welcome to come shoot with me. That includes 45 2.1 and his cohort. I will gladly demonstrate the difference between 7, 9 & 12" .223 Remingtons and 10, 12 & 14" twist .308Ws. I can also show then where the RPM Threshold is in any other rifle I have or they have. This offer is open to anyone of their choosing. That'S where I stand, ready and willing to demonstrate and prove the RPM Threshold is real. How about the others? Are they ready and willing to prove what they say? Odds are we'll hea r nothing from them or some excuse they have already "proved" it or they've sold the rifle etc. Point is they wouldn't put up in the past and I doubt they will now. I'll be going through Texas in February. Be glad to stop by char-gar's and show him what 2600 fps looks like out of a 14" twist. He could show me how he gets moa at 2100 fps with his 30-30 Marlin. Might even mame it up Tennessee way in March. Anyone want to show me HV/RPM with acccuracy?

Larry Gibson

[MBTcustom]

Larry, I talk to lots of people everyday, but it was you that told me about your offer in a thread just the other day, that was directly related to the rpm theory.
I started reading and pondering, and I found that I agree wholeheartedly with certain parts of the theory, especially if we are dealing with middle of the road cartridges.
The problem I have is that according to the rpm theory, you shouldn't be able to shoot a cast boolit out of a standard AR-15 any faster than 1650fps with accuracy.
I've seen that done way too often.
I'm just trying to square my own experience with the rpm theory, and they just don't line up.
I'm not kidding about buying you dinner either. You've helped me on several of my projects, and I owe you a chunk of sirloin and a tall frosty glass anyway.
I'm just very interested in this subject, and I'm looking to find where I stand on things.
That's a very good idea about getting several barrels in different twists and run controlled experiments on this subject. To tell you the truth, I'm honestly thinking about getting a high speed video camera some day, to see what happens when the barrel kisses the boolit goodby. I also talked with a man recently who seems to think it would be possible to create a transparent barrel out of ceramic, that would actually allow me to see the boolit through the whole process.
For the moment, I'm just trying to do what I can with what I've got (which I know is considerably more than most have) and try to draw good conclusions based on good science.
I apologize if I ran away with the keyboard and threw tact to the wind. I do appreciate your patience. I have a lot to think about.

PS, march may be a little soon to get a HV/Highrpm rig together, but you aught to swing in anyway.

[45 2.1]

This would be a good spot to tell the folks what happens when you shoot a 180 gr. boolit (or the very popular 311284/311299/314299) in a 14 twist..... either 308 or 30-06 users are welcome to explain. Those light boolits you're bragging about don't carry well at really long distances (500 yards and over for cast) in a 14 twist. Tell us how well or not they shoot. Of course, if no one speaks up, then we can surmise they know it doesn't shoot too well.


You have the ability and expertise to find out for yourself. Perhaps a good action and 3 identical barrels 26" long with 10, 12 & 14" twists chambered for the 30x57 and a good cast bullet such as the 311466 or the LBT 150 gr would give you the better answer. Larry Gibson

Larry.... a simple question/query was asked. What does your whizzbang 14 twist do with 200 gr. and over boolits..... not the light ones you're shooting.... perhaps your vaunted slow twist rifles won't shoot them accurately? A simple test at 1800 fps, 2100 fps and 2400 fps with the 311299 or 314299 would illuminate just what they do. Of course, if you don't reply with some groups, those wondering would have cause to doubt what you've said.

[Char-Gar]

Larry...

I have had a 1-14 twist 30-06 and it was the best shooting cast bullet rifle I have ever owned. I did not try and push bullet 2,600 fps, but if you say it can be done. I have no reason to disagree. I don't think I said anything to the contrary.

I did not say I got MOA out of that Marlin. I said I got "great accuracy", which means it shoot fully as well with cast bullets at 2,100 fps as it die with jacketed bullets at the same speed. In the case of this particular rifle that would 1.5 to 2 MOA depending on the day.

I am not challenging you on anything you have posted. Nothing you have posted does not square with my experience, so no need to get defensive.

I do wish you and Bobl could just ignore each other and not feel the need to duke it out over RPMs ever time the chance comes up. This has been going on for years and not much of value has been gained as the result. But you two just don't seem to be able to help yourselves.

I really can't be too critical of you guys as I have my own impulsive behaviors. I spent so many years as a professional busy body (Pastor) that I have an instinct to try and defuse conflict. I promise myself, I will just walk away from this conflict, but the old desire to make peace takes over. I will try one more time to mind my own business. My problem is I care allot more about people and their relationships that I do about some stupid holes in a paper target and how they got there.

I keep trying to find some middle ground that enfolds everybody's experience and thinking, but that is just not going to happen, and my wanting to make it so, won't make it so. At my age, you would think I would have given up jousting with windmills.

I long ago put Bobby on my ignore list, so I don't know what he says. I find my life better than way. It does make for less stress in life.

[Larry Gibson]

goodsteel

Larry, I talk to lots of people everyday, but it was you that told me about your offer in a thread just the other day, that was directly related to the rpm theory.

Yup, I'll shoot with anyone, anywhere I can, and am more than willing to back up what I say. Since I've always said the RPM threshold can be pushed up I'm also intensely interested in observing how others do it.....if they really do.

I started reading and pondering, and I found that I agree wholeheartedly with certain parts of the theory, especially if we are dealing with middle of the road cartridges.
The problem I have is that according to the rpm theory, you shouldn't be able to shoot a cast boolit out of a standard AR-15 any faster than 1650fps with accuracy.

Problem with that statement is what is a "standard" AR with regards to barrel twist. There are lots of 12" twists around, lots of 9" twists around and lots of 7" twists around. There are even quite a few 8 and 14" twist ARs around. Since the RPM threshold velocity is dependent on rate of twist what is the "standard AR"? Again the 1650 fps you use is a "limit" the way you say it. The RPM threshold is not a "limit".

I've seen that done way too often.

If you are talking about the "standard" AR with a 7" twist then are you sure what you have seen? I can load my own 7" twist AR to 1800 - 1900 fps and maintain 3 - 4 moa groups (10 shot) at 100 yards. That might look like it hasn't exceeded the RPM threshold but it has. If we shoot the same ammo at 200 yards we do not get the linear expansion of 6 - 8" groups we would expect. What we get is groups of 14" to not even on the 21x24" target. That is how we know the load has exceeded the RPM threshold. I have said many times exceeding the RPM threshold does not mean the bullet will lose rotational stability or keyhole. If the 3-4 moa accuracy at 100 yards is satisfactory to the AR shooter then he can blaze away. That does not mean his ammo does not exceed the RPM threshold, it just means he is satisfied with what he gets. However, when he decides to shoot at longer range odds are he will be sorely disappointed in the accuracy.

I'm just trying to square my own experience with the rpm theory, and they just don't line up.

As you "square up" the RPM threshold with your own experience base it on your own experience. Don't take my word for it or anybody else's here on this forum or any other. Do your own experimenting increasing the velocity in fast twist guns from below 120,000 RPM until you get to, say 180,000 RPM. Not the velocity where accuracy starts going south with testing at 100 yards. Then load 30 shots of the best group under the RPM threshold and 30 shots where the accuracy really went south over the RPM threshold. Test those with 10 shot groups at 50, 100 and 200 yards. You will find the load under the RPM threshold to give linear expansion of the groups as the range is increased. The groups with the load over the RPM threshold will give non-linear group expansion as the range increases with the groups getting quite large at 200 yards. This test is easily done with any '06 for instance having a 10" twist and a common cast bullet such as 311291. Using a medium burning powder such as 3031, 4895, 4064, etc. load to velocities of 1700 through 2300 fps. Then if you don't believe that do it with any other rifle with a 12" or faster twist.


I'm just very interested in this subject, and I'm looking to find where I stand on things.
That's a very good idea about getting several barrels in different twists and run controlled experiments on this subject. To tell you the truth, I'm honestly thinking about getting a high speed video camera some day, to see what happens when the barrel kisses the boolit goodby. I also talked with a man recently who seems to think it would be possible to create a transparent barrel out of ceramic, that would actually allow me to see the boolit through the whole process.
For the moment, I'm just trying to do what I can with what I've got (which I know is considerably more than most have) and try to draw good conclusions based on good science.

Then run the tests yourself and draw your own conclusions.

I apologize if I ran away with the keyboard and threw tact to the wind. I do appreciate your patience. I have a lot to think about.

Not a problem, I have a pretty thick skin about this subject now.

PS, march may be a little soon to get a HV/Highrpm rig together, but you aught to swing in anyway.

Might just do that. The youngest daughter is getting married in Florida which is the reason for the trip. The wedding is the reason I've not come up with a barrel for the 30x57 yet......:( Will be pulling the 5th whl so how far north I venture that time of year will be weather dependent. I'd sure like to make it to your place.

Larry Gibson

[Larry Gibson]

Char-Gar

I meant no offence. I would really just like to shoot with you and see how that Marlin does at 2100 fps at 100 and 200 yards whether it is moa or not. No criticism but just intensely interested is all. As you mention we agree more often than not. I respect your opinions and abilities and since the RPM threshold can be pushed up and you have done it I'd just like to see how is all. As to bobby and his cohort.......what can we say........I would really like to shoot with both of them anyway......could be fun.......

Again, my apologies for not getting my meaning across, no offence meant......:drinks:

Larry Gibson

[frnkeore]

A simple question, Larry.

If your RPM "threshold" isn't a limit, why do you doubt that people can exceed it and want witnessed proof of it? Inquiring minds would like to know. 1980's (subjective or not) technology doesn't always hold up, there is something call progress.

The best way to get crediblity in this matter is to shoot in CBA Matches (at least once a year), were the results are posted for all to see. They shoot score and group matches @ 100, 200 and 300 yards with all kinds of rifles (milsurp, hunter, production, heavy and unrestricted), plus 2 pistol classes.

Frank

[Char-Gar]

Larry..

That Marlin 336A is in the back of the safe. I have no had it out in years. About ten or twelve years ago, I got interested in finding out how fast you could really push a cast bullet in Microgroove barrels. Common wisdom at that time said 1,600 was about it and after that cast bullets would roll snake eyes. I pushed 2,000 rounds down the barrel of that rifle over a five month span, probing the limits of the 30-30 MG with five or six bullets.

I had/have a SAECO 305 which was supposed to be their 303 British bullet, but it is nothing but a fatten version of their 30-30 (N. 307) bullet. It proved to have the diameter and nose size for a perfect fit in the Marlin. Using No. 2 alloy and 3031 powder (and 4895), I had no problem turning in 2,100 fps with excellent accuracy. It really wasn't much of a trick, just good fit and a stout alloy.

The rifle has an El Paso made Weaver K 2.5 on it. When Bill Weaver died and Weaver sold out, they sold off their existing inventory for a song. I got several scopes from that deal. I was living in El Paso at the time.

They buried Weaver in a large above ground crypt in El Paso. They built this crypt over about four more graves and that resulted in a nice law suit. In the end Weaver is in his crypt which is holding down some more folks under it and the families got a very nice settlement out of the deal. They got some free graves from the cemetery and the stone were moved there, but nobody is there. They are all still under Bill Weaver. I got this from a funeral director there in El Paso.

[Larry Gibson]

frnkeore

Once again the RPM is not a limit, it is a threshold. That threshold, unlike a limit, can be moved up or down. If that threshold, for the components and rifle used, is crossed then accuracy will be lost to some degree. How much accuracy is lost depends on how far across the threshold the load has crossed. With the CM test mentioned above at 1800 - 1900 fps the accuracy lost was about 1 - 2 moa at 100 yards. At 200 fps the accuracy lost at 100 yards was 10+ moa. Above that accuracy was so lost the bullets wouldn't stay on the 21x24" target paper at 50 yards.

I don't doubt that many can push the RPM threshold up a bit. The example you gave (Mr. Craig), Char-Gar's 30-30, my own and bass ackwards work with the 311291 in the '06 and my own further work with fast twist AR .223s and 6.5 Swedes and numerous other rifle/cartridges further demonstrate that. It is not rocket science and I, and others, have explained numerous times how to do it. But when some want to claim 2400+ fps with moa accuracy using regular cast bullets in 10" or faster twist barrels.........let's just say the doubt creeps in, especially when those who claim such are willing to demonstrate such in front of reliable witnesses and further claim that only they and a couple others have unlocked the secret of the ages and can walk across the rice paper w/o leaving footprints.........

The technology Nobade has used seems to be a little more advanced than "'80s technology".

I don't quite grasp your thought process where shooting in CBA matches would gain "credibility" in this discussion??? In CBA matches accuracy is the objective is it not? So how would shooting above a component/rifles RPM threshold and lose accuracy gain any "credibility"? I do believe if you collate all the match results from the '80s technology in CBA matches to the present high state of technology you will find that 99.9999999999% ad nauseum of the loads used were in or under the RPM threshold for the load/rifle they were shot in.

Larry Gibson

[MBTcustom]

Larry..

That Marlin 336A is in the back of the safe. I have no had it out in years. About ten or twelve years ago, I got interested in finding out how fast you could really push a cast bullet in Microgroove barrels. Common wisdom at that time said 1,600 was about it and after that cast bullets would roll snake eyes. I pushed 2,000 rounds down the barrel of that rifle over a five month span, probing the limits of the 30-30 MG with five or six bullets.

I had/have a SAECO 305 which was supposed to be their 303 British bullet, but it is nothing but a fatten version of their 30-30 (N. 307) bullet. It proved to have the diameter and nose size for a perfect fit in the Marlin. Using No. 2 alloy and 3031 powder (and 4895), I had no problem turning in 2,100 fps with excellent accuracy. It really wasn't much of a trick, just good fit and a stout alloy.

The rifle has an El Paso made Weaver K 2.5 on it. When Bill Weaver died and Weaver sold out, they sold off their existing inventory for a song. I got several scopes from that deal. I was living in El Paso at the time.

They buried Weaver in a large above ground crypt in El Paso. They built this crypt over about four more graves and that resulted in a nice law suit. In the end Weaver is in his crypt which is holding down some more folks under it and the families got a very nice settlement out of the deal. They got some free graves from the cemetery and the stone were moved there, but nobody is there. They are all still under Bill Weaver. I got this from a funeral director there in El Paso.

That's a real hoot!

[Larry Gibson]

45 2.1

Larry.... a simple question/query was asked. What does your whizzbang 14 twist do with 200 gr. and over boolits..... not the light ones you're shooting.... perhaps your vaunted slow twist rifles won't shoot them accurately.

A simple test at 1800 fps, 2100 fps and 2400 fps with the 311299 or 314299 would illuminate just what they do. Of course, if you don't reply with some groups, those wondering would have cause to doubt what you've said.

[/I]?

Bobby.....for you, a simple answer for the simple "query"........don't know about over 200 gr cast bullets but I did run a test not too long ago for a fellow up in Alaska who wanted to know how the 311299 would do in a 14" twist. As expected in my "whizzbang" it did not do well below 2000 fps. However at 2300 - 2400 fps with AA4350 it did quite well running 1 1/2 moa at 100 yards. I really didn't test much more than that as I suggested a 12" twist would be better for 200 gr cast and heavier. Actually I ran out of case capacity with the "whizzbang" rifle considering it's .308W chambering. Now perhaps Nobade with his 14" twist 30-06 could do better given the larger case capacity with powders such as H4831 or RL22 but that's up to him.

Now a simple question for you 45 2.1;

Why on earth would I get a 14" twist .308W Palma barreled rifle designed to shoot 145 - 155 gr bullets and want to shoot 200+ gr cast bullets in it? Particularly when the idea was to push the 14" twist to the RPM threshold at 2700 fps. Considering you can't reach that velocity in a .308W (regardless of the 27.5" barrel) with a 200 gr or heavier bullet safely what would be the point? I can't even get there with slower powders using the 160 gr 311466 because of lack of case capacity. That is why I have bought a 122 gr NOE 311465 mould to test. Point is I did not get the 14" twist Palma rifle to shoot heavier bullets in. I have 12" twist .308s for that or 10" twist '06s. Even with those I've no allusions of moa accuracy with a 311299 at 2400 fps. Perhaps at 2200 - 2300 fps in the 12" twist for useable hunting accuracy though as I've already been there and done that.

Asking that "simple question" of shooting 200+ gr cast in a .308W barrel is about as sensible as if I asked you why you can't shoot a 311359 accurately at 3000+ fps out of your 10" twist '06. The '06 is certainly capable of that velocity with that weight bullet. But we all know the bullet is way out of line for probable best stabilization isn't it. So who are we trying to fool here?
with such a "simple question/query"?

Larry Gibson

[Larry Gibson]

Char-Gar

Excellent explanation of how to get there by pushing the RPM threshold up with the right alloy, bullet design, fit of bullet and powder for the case capacity/bullet weight. I do not doubt that 30-30 load can shoot well at 2100 fps.

Love the Weaver story too, it is a hoot.

Larry Gibson

[Char-Gar]

Larry...A good dose of ignorance helps at times. I had been shooting Winchester 30-30 leverguns for many years at full snort velocity and I knew they were 1-12 rifled. I assumed all 30-30s were so rifled. It was not until after I had achieved my goal with the Marlin, did I learn that Marlin rifles their barrels 1-10.

[frnkeore]

"Once again the RPM is not a limit, it is a threshold. That threshold, unlike a limit, can be moved up or down. If that threshold, for the components and rifle used, is crossed then accuracy will be lost to some degree."

Again, if it isn't a limit, why dispute what people say they can do? Long before I new it wasn't possible (approx 1995), I spun my 323471, 8x57 to 180,555 rpm with 2" grouping in a rifle that is good for 1.5 with Rem 185 gr jacketed.

You need to be inclusive (in what has proven to be) and up to date in presenting your "threshold", things can and do change.

You gain two things when shooting in competition:

1. Pushing limits with new ideas or improving on old.

2. Undeniable, indisputable proof of what your shooting componts can and will do.

Since there have been so many (including yourself) that have exceeded 140,000 RPM, why not come current and raise your threshold to 160,000?

[Larry Gibson]

Yup, sometimes ignorance is bliss. Back in the day when I 1st started with cast (late '60s) I had a 10" twist '06 and a 10" twist .308W. Found best accuracy was in the 1900 - 1950 fps range (got my 1st Oehler in '74) with my 311041 depending on the powder used. When I started using the 30-30 in a M94 rifle I just held the velocity to 1900 fps or so thing that was as good as it would get. Wasn't until I read that article questioning whether it was psi or RPM that was adversely affecting cast bullet accuracy that I pushed the M94 30-30 up to 2200+ fps with the same accuracy I could only get at 1900 - 1950 fps in the .308 and '06. Then I got ahold of a M70 .308W and a Browning '06 both with 12" twist and lo and behold I could get the same accuracy at 2200+ fps that the 10" twists would get at 1900 - 1950 fps. Then along in there I had a 222 Rem with 14" twist and a M700V .223 with 12" twist. Accuracy went south in the M700V at 2200+ fps but held at 2400+ in the 222 Rem with the same cast bullet. That's what really got me to thinking about and studying the adverse effect of RPM on cast bullets. Then having chronographed a multitude of cast loads in rifles of various cartridges and twist I discovered over time that accuracy almost always went south between 120,000 and 140,000 RPM regardless of the actual velocity. Those cartridges loaded with the slower burning pistol powders generally lost accuracy at the bottom end and with medium burning powders at the top end of that RPM range given the same twist and the same cartridge. I then learned that with slower powders the RPM threshold could be pushed up. Also with better designed and fitting cast bullets it could be pushed up. Other things were learned along the way. After broaching the subject here I was asked what it was called so I decided to call it the RPM threshold instead of a "limit' because it was not a limit that is set. It is more like a threshold (doorway, crossing, etc.) where it can be moved but if it is crossed (with the load/components/twist/cartridge used) accuracy will go south. Of course I studied the laws of ballistics heavily along the way to further understand what was happening. Yup a good dose of ignorance can be helpful at times but I do appreciate really knowing the where's and why fors of what is happening.

Larry Gibson

[Larry Gibson]

frnkeore

Since there have been so many (including yourself) that have exceeded 140,000 RPM, why not come current and raise your threshold to 160,000?

Compared to the vast majority of cast bullet rifle shooters there really aren't that many who have pushed the threshold successfully to 160,000 RPM. It is not easy to do successfully and consistently. It takes knowledge, experience and the right equipment to do it. As I state in the sticky on the RPM threshold twist rates; "Let us keep in mind the RPM threshold most often falls in the 120,000 to 140,000 RPM range with regular lube groove cast bullets." we find that to be valid for the majority of cast bullet rifle shooters. If you do consistently shoot the 323471 at such RPM accurately and w/o non-linear expansion of group size as the range increases you fall into a very small group of caster/shooters who can successfully push the RPM threshold upwards. Be satisfied that you can. Thus I see no change necessary or a need to be "inclusive". The fact that I've stated over and over again that the RPM threshold can be moved up should be sufficient.

Your insistence on competition shooting with cast bullets at HV/RPM should be directed at 45 2.1 and his cohort, the departed starmetal and perhaps one other. They are the ones claiming moa and recently 1/2 moa accuracy and HV/RPM. I do not claim such so competition is somewhat misdirected at me. The accuracy I claim wouldn't be competitive. Besides I have competed in a lot of matches over the years and did quite well for myself. But haven't we covered all this "what are your qualifications" before? Also if you'd check the CBA records for the last....quite a few years......you'll find many, many slower twist barreled rifles with lighter weight cast bullets at HV doing quite well.

BTW; I do get up through Oregon every year, perhaps you'd like to show me those 2" consistent groups with that 323471 at 180,000 RPM? BTW does it group into 4" at 200 yards? Reason I ask is my own 8x57 with that bullet shoots moa or better with 5 or 10 shot groups at 100 yards at 1850 - 1900 fps (which is under the guess what?) . It also shoots my hunting load with the same bullet into 2 - 2.5" at 160,000 RPM. But guess what it shoots into at 200 yards? 8 - 10" groups which is non-linear expansion and an indication of what? Must be why I limit it's effective range to 150 yards where it stays inside 4" groups. By the way I'm measuring the consistent accuracy with 10 shots for group. Thus if your own HV/RPM load is not shooting into 4" groups at 200 yards then guess what?

So if I get up that way you gonna show me how it's done?

Larry Gibson

[Char-Gar]

In 1963, I got a Winchester 70 in 375 Holland and Holland. It came with a Lyman mold (IIRC 375449) that weighted about 260 grains checked and lubed. There seemed to be no limit how fast you could push that bullet. My tolerance for recoil quit before the accuracy went south. I think the twist was 1-14, but I am working from some very old memory. I shot a number of Texas Whitetail with that rifle and bullet and it always did the job.

[45 2.1]

a simple answer for the simple "query"........don't know about over 200 gr cast bullets but I did run a test not too long ago for a fellow up in Alaska who wanted to know how the 311299 would do in a 14" twist. As expected in my "whizzbang" it did not do well below 2000 fps. However at 2300 - 2400 fps with AA4350 it did quite well running 1 1/2 moa at 100 yards. I really didn't test much more than that as I suggested a 12" twist would be better for 200 gr cast and heavier. Actually I ran out of case capacity with the "whizzbang" rifle considering it's .308W chambering. Now perhaps Nobade with his 14" twist 30-06 could do better given the larger case capacity with powders such as H4831 or RL22 but that's up to him.
Larry Gibson

Just nailing things down............ Nobade is free to do that if he wishes. It would probably help some people if he did.


Why on earth would I get a 14" twist that is why I have bought a 122 gr NOE 311465 mould to test. Point is I did not get the 14" twist Palma rifle to shoot heavier bullets in. I have 12" twist .308s for that or 10" twist '06s. Even with those I've no allusions of moa accuracy with a 311299 at 2400 fps.
Larry Gibson

There you have it folks. That is what the 14" twist rifle is for.............. the lower half of the boolit weight spectrum for the caliber.

[swheeler]

Again! :(

[frnkeore]

Yes, indeed, Larry. My only request is that you bring your MOA 2700 fps rifle and bullets with you. If you can make it on the 4th Sat. of the month, we will have plenty of wittnesses. We will shoot at both 100 and 200 yards. A side note to the 2700 fps......... why shoot such a low BC bullet at HV, especially at 200 yds?

BTW, in ASSRA, PB bullets @ ~1450 fps, we are fining that the difference between 100 & 200 yards is more in the order of 2.5 - 4 to 1.

I just shot five, 5 shots groups averaging .545 @ 100 and 10 shot 1.440 at two different matches in Oct. A friend shot .388 five, 5 shot groups @ 100 and 1.475 10 shot @ 200.

We will shoot this as a regualar monthly match, this coming year.

Frank

[Larry Gibson]

45 2.1

Once again you get it wrong......

There you have it folks. That is what the 14" twist rifle is for.............. the lower half of the boolit weight spectrum for the caliber.

Since when was 200 gr the dividing point between the lower and upper half of the .30 cal cast bullet spectrum. There are a lot more 30 caliber cast bullet designs under 200 gr than over 200 gr. Additionally my 14" twist rifle is for the .308W. In case you've not noticed 200 gr was/is the heaviest jacketed bullet available in factory ammunition for the .308W. A prudent individual would observe that to be the top end not the "dividing line" separating the upper and lower halves......whatever that might be.........

Obviously you've not shot any CF .30 cal cartridge with a 14" twist barrel capable of reaching 2700 fps or you would know the 14" twist handles the "middle spectrum" of .30 cal cast bullets (160 - 180 gr....including the one of your design:lol:) just fine, especially at the velocities you dream of.......perhaps the "guru" should acquire a 14" twist .308W or '06 with a 26"+ barrel and find out for himself........

Larry Gibson

[Larry Gibson]

frnkeore

Yes, indeed, Larry. My only request is that you bring your MOA 2700 fps rifle and bullets with you. If you can make it on the 4th Sat. of the month, we will have plenty of wittnesses. We will shoot at both 100 and 200 yards. A side note to the 2700 fps......... why shoot such a low BC bullet at HV, especially at 200 yds?

You should really pay a tudge more attention to what I write. The 14" Palma rifle I have does not shoot moa at 2700 fps and I never said it did. What I have always said it shoots 1 1/2 moa at 2600 fps with the 311466. The BC has nothing to do with it. As I explained already the object of using that bullet was to push up or cross the RPM threshold for the 14" twist barrel. Do you know what that is at 140,000 RPM? It is 2722 fps. I couldn't get there with AA4350 or any slower burning powders with the 311466. Closest I got was 2650 fps with a slightly compressed load at 42,000+ psi. Tried faster powders but they actually began lowering the RPM threshold because the psi was considerably higher and thus the acceleration rate was quicker. That was damaging/unbalancing the bullet more and the RPM threshold was thus lower. So, a lighter bullet is in order to achieve 2700+ fps with the .308W chambering and 27.5" barrel. Simple as that.

As to a practical matter of the 311466 the BC is sufficient that at 2600 fps it still is doing well enough at 300 yards to kill deer, pigs and coyote's all day long. The accuracy is there also. Yes I could get a long nosed cast bullet but we know a long pointy unsupported nose will not hold up well under acceleration sufficient to get 2700+ fps out of the .308W. The RPM threshold will be much lower because accuracy will go south much sooner. Been there and done that with the 311413 and to an extent 45 2.1s 180 gr. Have to say 45 2.1s 180 held up a lot better than the 311413.

BTW, in ASSRA, PB bullets @ ~1450 fps, we are fining that the difference between 100 & 200 yards is more in the order of 2.5 - 4 to 1.

I just shot five, 5 shots groups averaging .545 @ 100 and 10 shot 1.440 at two different matches in Oct. A friend shot .388 five, 5 shot groups @ 100 and 1.475 10 shot @ 200.

That is good shooting but a comparison of 5 shot groups at 100 yards to 10 shot groups at 200 yards is apples to oranges. You need to be "inclusive" and use 10 shot groups at both ranges to make a valid comparison. The conditions are much different during a 10 shot string of gun, weather conditions and shooter than during the much shorter 10 shot string.

I will surely try to make it but I still fail to see what pushing the RPM threshold at 2600 - 2700+ fps to inaccuracy has to do with match competition at 1400 fps for accuracy? Seems rather oxymoronic to me........Perhaps you could shed some light on the validity of the comparison?

Larry Gibson

[singleshot]

IF you can do that so the cast bullets are then perfectly balanced in flight with the center of mass (form), center of gravity and the center spin all perfectly coinciding there would be no RPM threshold. Larry Gibson

Except there will still be an RPM hard limit where the boolit tears itself apart. I have no idea off the top of my head what that would be, BTW. I suppose in this case, accuracy would still suffer. :-)

[MBTcustom]

Except there will still be an RPM hard limit where the boolit tears itself apart. I have no idea off the top of my head what that would be, BTW. I suppose in this case, accuracy would still suffer. :-)

That is a question that I have boring a hole in my brain. I mean, a copper jacketed bullet can shed the jacket at which point you are obviously *****, but a cast lead boolit? If its done right, there are no weak spots, so what is going to get "torn apart"? Its a homogeneous projectile. I could see it tumbling, and I could see it folding over on itself, but it's all one piece, so I don't know if it would go to pieces like the classic 22 swift situation.

[singleshot]

Now, this whole discussion brings up another question: why would we expect the same RPM threshold between .22 and .3 cal boolits? .22 cal boolits SHOULD be able to handle higher RPMs without deforming. HELP?!?!?!

[MBTcustom]

Now, this whole discussion brings up another question: why would we expect the same RPM threshold between .22 and .3 cal boolits? .22 cal boolits SHOULD be able to handle higher RPMs without deforming. HELP?!?!?!

Gets the ol grey matter to quivering don't it? LOL!

[singleshot]

That is a question that I have boring a hole in my brain. I mean, a copper jacketed bullet can shed the jacket at which point you are obviously *****, but a cast lead boolit? If its done right, there are no weak spots, so what is going to get "torn apart"? Its a homogeneous projectile. I could see it tumbling, and I could see it folding over on itself, but it's all one piece, so I don't know if it would go to pieces like the classic 22 swift situation.

At the molecular level, does it really matter if it's homogeneous? Lead molecules don't bond very tightly to one another. All the outside molecules will have the highest acceleration. However, the force is acceleration * mass. The further you go to the outside circumference, the higher the acceleration, but the lower the mass. So where do the max forces occur inside the projectile? Not sure.

[singleshot]

Gets the ol grey matter to quivering don't it? LOL!

Yep. Sure does! I always close my 'puter when my head starts to hurt too badly! LOL!

[frnkeore]

Larry,

1. While I will also shoot my PB rifle in the match, I will have my M48 along, too.

2. While I agree that one 5 shot group is easier, I don't agree that the average of five consecutive 5 shot groups is easier.

3. You should be familar with the paper work below. This .600, ten shot group was shot with Barry Darr's M43 the same day as the .545 average, in testing a bullet that wasn't quite as accurate as the .545 & 1.440 group bullet. Witness by Barry Darr and 2 others.

Frank

87338

[Nobade]

[QUOTE=45 2.1;2473462]Just nailing things down............ Nobade is free to do that if he wishes. It would probably help some people if he did.[QUOTE]

I don't have a mould for #311299 but I do have one for the Lee 200gr. bore rider, and a bunch of WXR powder. I will give it a try next time I get a chance to go out and do some testing. I am actually curious as to how this works as well. I was originally looking at maxing out at 180gr and have several moulds in that weight range but it will be fun to see what it will do with 200gr.

-Nobade

[Nobade]

Except there will still be an RPM hard limit where the boolit tears itself apart. I have no idea off the top of my head what that would be, BTW. I suppose in this case, accuracy would still suffer. :-)

Haha - I have seen this in my '96 Swede. Shooting the cruise missile boolit, if I get up past 2000 fps the boolits break in half. I suspect when the nose hits the rifling and spins up, it breaks in one of the grooves before the back half gets spun up. Whatever is happening, I get two hits somewhere down range and even shot my truck once even though it was way out of the line of fire. So yes, accuracy does suffer if you tear the boolits apart. Once I started paper patching that same boolit, it stopped doing that and shoots accurately at 2400 fps. I still haven't figured out how the paper keeps that from happening but I am happy it does.

-Nobade

[Larry Gibson]

Nobade

What alloy were you using with the CMs that broke in half? I've only shot about a hundred of them now and only 40 were at 2000 - 2500 fps. started getting keyholing around 1950 - 2000 fps. I never go any indication of the hits on target or double impacts in the berm that the bullets had broke apart. I was using 80/20 linotype/lead with a BHN of 19-20. I can easily see how what you say could happen. There is a lot of mass in that long unsupported nose and not really much diameter at the bottom of the lube grooves.

Given the inertia of the nose mass resisting the fast spin the nose could definitely twist apart. This is one of the things that no doubt happens to the long unsupported noses of more pointed cast bullets, especially those with a scraper groove like the 311413. They may not twist in two but the bend to one side and/or get distorted which unbalanced them. The faster the twist with a given acceleration rate the more the damage. Perhaps this is what goodsteel and others are referring to by faster twists being "harder" on bullets than slow twists? If so we are in agreement as I was thinking of skidding or stripping. The faster the twist at a given acceleration rate the more damage/unbalancing will happen from the torque to the bullet and overcoming the inertia of the bullet.

Then if we think about what is happening to the bullet in that way the equal amount of unbalancing required for the cast bullet will happen at a lower velocity in a fast twist than in a slow twist. The torque required for equal unbalancing of the bullet is produced by the same RPM in both. Equal RPM occurs at a lower velocity in the fast twist than it does in the slow twist. Amazing!

Thanks for the train of thought Nobade, we may have made things a lot clearer regarding what is happening during the internal ballistics phase.

Larry Gibson

[MBTcustom]

Nobade

What alloy were you using with the CMs that broke in half? I've only shot about a hundred of them now and only 40 were at 2000 - 2500 fps. started getting keyholing around 1950 - 2000 fps. I never go any indication of the hits on target or double impacts in the berm that the bullets had broke apart. I was using 80/20 linotype/lead with a BHN of 19-20. I can easily see how what you say could happen. There is a lot of mass in that long unsupported nose and not really much diameter at the bottom of the lube grooves.

Given the inertia of the nose mass resisting the fast spin the nose could definitely twist apart. This is one of the things that no doubt happens to the long unsupported noses of more pointed cast bullets, especially those with a scraper groove like the 311413. They may not twist in two but the bend to one side and/or get distorted which unbalanced them. The faster the twist with a given acceleration rate the more the damage. Perhaps this is what goodsteel and others are referring to by faster twists being "harder" on bullets than slow twists? If so we are in agreement as I was thinking of skidding or stripping. The faster the twist at a given acceleration rate the more damage/unbalancing will happen from the torque to the bullet and overcoming the inertia of the bullet.

Then if we think about what is happening to the bullet in that way the equal amount of unbalancing required for the cast bullet will happen at a lower velocity in a fast twist than in a slow twist. The torque required for equal unbalancing of the bullet is produced by the same RPM in both. Equal RPM occurs at a lower velocity in the fast twist than it does in the slow twist. Amazing!

Thanks for the train of thought Nobade, we may have made things a lot clearer regarding what is happening during the internal ballistics phase.

Larry Gibson

The way I see it is this:
I'm using the paper patched boolit as a baseline for determining the RPM threshold of a certain cast boolit. The only reason they are different is because of something that is happening with the internal ballistics.
I see that a boolit begins it's spin with the nose being engraved by the rifling, so at one point the boolit is being twisted by the barrel because the rifling is telling the nose to "spin spin spin!!!" but the base hasn't gotten the message yet because lead is so malleable (even in a high Linotype mix). Ordinarily this is not a problem because the tail of the boolit is much closer to the nose.
my father always told me "if you want to make something weak, first make it strong". I wonder if a boolit made of 50/50WD would twist, but be maleable enough to hold together and not break.
Of course, I am making the assumption that the issue is happening in the throat of the rifle and not at the crown. Hmmmmmm. I'll go ask Boolette. She rides boolits all the time, so she should know. LOL!

Still, when the boolit is in the middle of the barrel it is trapped and cannot get away. "It's safe" in a manner of speaking. Once it has crossed the crown the entire boolit has inertia on it's side, and there is nothing that is going to directly effect that, so I doubt it would break at that point.

[Larry Gibson]

frnkeore

That is excellent loading and shooting of cast bullets no doubt about it. It is certainly a goal where accuracy is the criteria. However, with the discussion of the RPM threshold and it's adverse affect on accuracy there are 2 aspects of consideration.

The 1st is accuracy. Not the ultimate level of accuracy as sought by CBA match competitors but the best level of accuracy that a set of components is capable of in a given rifle. That may be 1/2 moa, it may be 1 1/2 moa or it may even be 3 moa. It is simply the best accuracy (based on a sufficient sample size of 7 - 10 shots) that set of components is capable of in that rifle.

The 2nd consideration is the velocity/RPM. At what velocity/RPM level is the best accuracy that set of components in that rifle at. An additional aspect of velocity/RPM consideration when determining the RPM threshold is the velocity/RPM where consistent accuracy is lost and non-linear expansion of the group size occurs as the range increases.

I'd venture to say that every cast bullet shooter developing loads in CF rifles with 12" twists or faster has found a load that meets the 1st consideration. That "accuracy load" is the goal of all cast bullet shooters, yes?

I'd also state with 100% assurance that the same 100% of cast bullet rifle shooters have, in the load development, gone above that "accuracy load" and found the accuracy went south. That's why they backed off to the "accuracy load". What they found when the accuracy went south was the RPM threshold for that set of components in that rifle. They just didn't recognize it as such. Now probably 99.999999999% of the rifle cast bullet shooters are perfectly happy with such an "accuracy load" and stick with it. It is only a few of us who venture to higher velocity/RPM. We may push the RPM threshold a bit higher by improving on or changing components but at some point, usually well below the rifles velocity capability with that weight bullet, the load will hit the RPM threshold and consistent accuracy will go south.

My hat is off to whoever shot that group BTW. When looking for or comparing accuracy at 100 and 200 yards for linear or non-linear expansion of the group size to be valid the group sample must be sufficient (the reason for 10 shot groups) and they must be shot under the same conditions. Shooting a 5 shot group or multiple 5 shot groups over the course of a day or two is different conditions that shooting a straight 10 shot group. A valid comparison is a 10 shot group fired at 100 yards and a 10 shot group fired at 200 yards under the same conditions (as close as we can have them) by the same shooter from the same bench preferably on the same day.

Also in discussion of your increase in group size at 100 and 200 yards even using the 5 and 10 shot groups shows the linear expansion plus the expected additional effects of double the wind effect and other conditions. In the example all are extremely accurate and under the RPM threshold. I suggest you take a 10" twist '06, some 4895 (suggest a Dacron filler even though you don't use one) and load a 311291 or similar cast bullet in test strings of 28 gr and 36 gr. Shoot 10 shots for group at 100 yards with each load. Then shoot a 10 shot group at 200 yards with each load. Compare each loads 100 and 200 yard groups for linear expansion. The 28 gr load will give linear expansion (no it won't be exactly double but it will be close) . The 200 yard group expansion of the 36 gr load will not be linear to it's 100 yard group and it will probably be considerably larger than the 28 gr group. That will show you the adverse affect of crossing the RPM threshold.

If you want to find the RPM threshold for that set of components then load 10 shot test strings from 26 gr 4895 to 36 gr 4895 in 1/2 gr increments. Test at 100 yards and observe how groups size will tighten to the best group and then get larger. Load 20 shots each of those loads after the best accuracy group. Shoot 10 shot groups at 100 and 200 yards with each of those loads. Compare the linear expansion of each load between its 100 and 200 yard groups. You will see where the RPM threshold has been definitely crossed as the expansion ratio will be non-linear. As the load increases you will also note the non-linear expansion ratio also increases. That shows that as the RPM increases the adverse affect on accuracy increases.

A simple enough test for anyone to accomplish if one wants proof positive the RPM threshold is real.

Larry Gibson

[felix]

Nobade, the paper acts as a bearing surface. You will note that the big bullets fired by the big naval guns have a very short bearing surface just for the reason you have "discovered". ... felix

[frnkeore]

I'd also state with 100% assurance that the same 100% of cast bullet rifle shooters have, in the load development, gone above that "accuracy load" and found the accuracy went south. That's why they backed off to the "accuracy load". What they found when the accuracy went south was the RPM threshold for that set of components in that rifle. They just didn't recognize it as such. Now probably 99.999999999% of the rifle cast bullet shooters are perfectly happy with such an "accuracy load" and stick with it. It is only a few of us who venture to higher velocity/RPM. We may push the RPM threshold a bit higher by improving on or changing components but at some point, usually well below the rifles velocity capability with that weight bullet, the load will hit the RPM threshold and consistent accuracy will go south.

The above is JUST a Theory, nothing else. It doesn't take into account the hard work that shooters put into delevoping their loads and it doesn't address barrel harmomics. Barrel harmomics alone blow your theory out of the water. Different barrel metals, contures and thicknesses, vibrate at different rates. Getting a barrel to release the bullet at the same place in the cycle, means more to accuracy that any one thing. If you think that the accuracy is going to be the same just because the velocity is the same, your WRONG! At high cast bullet velocity, bullet lube can make a big difference, also.

If you want to make believers out of us, you need to do as I suggested before, mount 10, 12, and 14 twist barrels on the same well prepared rifle, shoot 10, ten shot groups, have a skilled match shooter (not you, as that wouldn't make it a blind, unbiased test) shooting the groups w/o knowing the twist of the barrel. And make sure all groups are witness by a unbiased party.

My hat is off to whoever shot that group BTW. When looking for or comparing accuracy at 100 and 200 yards for linear or non-linear expansion of the group size to be valid the group sample must be sufficient (the reason for 10 shot groups) and they must be shot under the same conditions. Shooting a 5 shot group or multiple 5 shot groups over the course of a day or two is different conditions that shooting a straight 10 shot group. A valid comparison is a 10 shot group fired at 100 yards and a 10 shot group fired at 200 yards under the same conditions (as close as we can have them) by the same shooter from the same bench preferably on the same day.

1. If your infering that I didn't shoot that group, I'd be happy to supply you with 2 of the witnesses phone numbers to verify it!!!

2. If you think that shooting 5 consecutive five shot groups (unbroken string of 25 shots, not a day or 2) is easier than one 10 shot, I suggest that you have someone witness your attemp at it and get back to us with your results.

3. There is no way to directly compare 10 shot groups at 100 and 200 yard but, in a tunnel. Even if you had targets at both ranges and alternated shots between them. It would take twice as long and there for the conditions wouldn't remain the same as a single 10 shot group.

4. If you think that 100 and 200 yard groups are exactly 2 to 1, I'd suggest that you study the record of CBA or even high power matches, they are not! You can even have smaller grouping at longer ranges with the same load combination. Target shooters know that!

Frank

[felix]

[COLOR="#0000FF"] If you want to make believers out of us, you need to do as I suggested before, mount 10, 12, and 14 twist barrels on the same well prepared rifle, shoot 10, ten shot groups, have a skilled match shooter (not you, as that wouldn't make it a blind, unbiased test) shooting the groups w/o knowing the twist of the barrel. And make sure all groups are witness by a unbiased party. Frank

The Warehouse of distinction in Houston is closed, and has been since the early '80s. Yes, the man of the house can do it in three shots, not ten. If you want statistics, you need 30 shots. ... felix

[Larry Gibson]

frnkeore

You really need to get that burr out from under your saddle. You did not state you shot the group. If you shot the group then my hat is off to you sir.

Barrel harmomics alone blow your theory out of the water. Different barrel metals, contures and thicknesses, vibrate at different rates.


I've yet to encounter a match barrel that will throw groups from 4" at 200 yards to 12 -15" groups based on "harmonics or "nodes". Sorry but barrels, especially heavy match barrels, just don't "node" that much with hard jacketed bullets screeching down that steel tube let alone a much softer cast bullet. As with 45 2.1 and his banned cohort you are wanting to compare the accuracy of one rifle to the next. That is not what is needed here. It is the accuracy of individual rifle that is compared to its own accuracy that gives us the information. Matters not if one rifle shoots 1 moa, the next rifle 1.5 moa and the 3rd rifle 3 moa at 100 yards. It is not the comparison of those against each other. The comparison comes when the accuracy loss and where (velocity/RPM) it occurs as to each rifle.

Example; If the 10" twist rifle shoots 1.1" group at 1900 fps at 100 yards and a 2.3" group at 200 yards we have a good load. If at 2000 fps at 100 yards the group opens to 1.5" and at 200 yards the group is 4.5" then the assumption is the load crossed the RPM threshold at 2000 fps. The reason is 2 fold; los of accuracy at 100 yards at 2000 fps and the non-linear group expansion with that same load at 200 yards.

If the 12" twist shoots a 1.5" group at 2150 fps at 100 yards and a 3.2" group at 200 yards we can say the load is under the RPM threshold. If the rifle shoots a 2.2" group at 2400 fps at 100 yards and a 9.5" group at 200 yards we can say the load has crossed the RPM threshold.

If the 14" twist rifle shoots a 3" group at 2600 fps at 100 yards and a 5.9" group at 200 yards the load has not crossed the RPM threshold. If at 22700 fps the group at 100 yards is 3.9" and at 200 yards the group is 12+" we can again say the load has crossed the RPM threshold.

So you see from those 3 examples that the slower twists showed increased velocity while maintaining consistent accuracy as compared to themselves . At when the loads crossed the RPM threshold they all lost accuracy and expansion at longer range was non-linear. Note also the point where accuracy was lost with each twist was pretty close to the RPM threshold of 140,000 RPM even though the velocity was different for each rifle as was the actual accuracy (size of the groups).

I don't know how to explain it any clearer to you than that.

It is easier to shoot one 5 shot group than it is easier to shoot one 10 shot group. That is the point. Shooting 10 shot groups at 100 and 200 yards on the same day in close to the same conditions is really not difficult at all. It shouldn't be anyway, especially for someone of your claimed experience. I've been to enough belly matches where we shot five 22 shot strings prone position with no support using iron sights in a day plus pulled targets to know that shooting two 10 shot strings pretty much back to from a bench at 100 and 200 yards isn't difficult at all. Been to enough bench rest matches and smallbore matches at 50 and 100 yards to know it's not all that difficult either.

In do so to see if the rifle/load has exceeded the RPM threshold you are not trying to squeeze the smallest group down to the last .0005 of an inch. It's not that difficult, period. If you are shooting off a bench and a load at 1900 fps gives 1.5" groups at 100 yards and 3 - 4" groups at 200 yards and then you shoot a load at 2000 fps and it gives a 2" group at 100 yards and a 6" group at 200 yards it's not "nodes" or "harmonics" either. Its not even a matter of 1/2 - 1" difference in group sizes between 100 and 200 yards. The difference in non-linear expansion between the 100 and 200 yard groups will be significant.

Run the test with an '06 I mentioned earlier, observe the marked loss of accuracy and non-linear expansion between 100 and 200 yard groups when the RPM threshold is crossed and then come back with your conclusions. A study of CBA records of groups shot under the RPM threshold tells us nothing about what happens when the bullets cross the RPM threshold. Those records only tell us that some damn fine shooting was done. So quit doing as 45 2.1 does and talk about what others do, go run the test I mentioned and see for yourself. Or, if you want to see what someone else is accomplishing read what Nobade is doing in this thread and what the others have found regarding the RPM threshold in this thread. Or it would seem your whole point is simply to argue with me once again. If that is the case I won't respond to any more of your questions here until you run the test for yourself.

Larry Gibson

[geargnasher]

Nobade, the paper acts as a bearing surface. You will note that the big bullets fired by the big naval guns have a very short bearing surface just for the reason you have "discovered". ... felix

Obturation rings, I believe they are called. Usually less than half the caliber "long".

Goodsteel, your father's advise is pertinent here, expansion on game isn't the only reason to use a 'weak', flexible alloy for high velocity and fast twists, at least to a point (22-2600 fps depending on caliber) where the torsional bearing surface strength becomes the weakest link and accuracy begins to suffer. There are other ways to get HV results, but rich, brittle alloys haven't worked very well for me.

Gear

[TXGunNut]

First of all, Nobade, that's awesome results in your new rifle! Congrats!
I'm relatively new to this CB game so this thread and materials linked here have taught me quite a bit. My 336 is what taught me the principles behind the RPM threshold because it's behavior is very well explained by Larry's writings on this subject. I don't doubt CharGar's results with a very similar rifle, I just know mine won't do it with loads I've tried because I was way over the threshold for this particular load and rifle. I must admit that I'd be happier if we could absolutely state that the RPM limit of HT'd WW alloy was 135,239. It's not an absolute limit as Larry has patiently explained (and explained, and explained, and...) because there are several factors that move this threshold up and down.
Larry, on your trip thru Texas mi casa es su casa. I'm a member of a private range a few miles down the road but I can't dispute your assertions on the RPM threshold, simply affirm them based on my limited testing. Back to our earlier posts on the 35 Rem we are limited by case capacity, not the RPM threshold...much like the .308W. I guess that's one reason why I built the 35 Whelen.
Awesome thread, guys! I wish Nobade continued good fortune with his new rifle and hope he isn't too upset about this epic hijack.

[45 2.1]

[COLOR="#0000FF"] You can even have smaller grouping at longer ranges with the same load combination. Target shooters know that! Frank

I've found the same thing Frank. It all depends on how the boolit is launched. As far as proving things as Larry presumes with very poorly shooting rifles, that is a pipe dream.

[LynC2]

Just a thought: perhaps there is something to be gained with a gain twist with very long cast boolits as per Noblade's experience in the 6.5 Swede.

[frnkeore]

All I can say to what you've just written is LOL

First things first, Larry, I have suggested the scientific blind test twice to prove your "theory" I'll do as you suggest AFTER you do what I have suggested.

Study the records at different yardages for CBA, ASSRA, ISSA and High Power. Get back to us with ducumented referances of the group difference at 1, 2 and 300 yards.

In the sciencific world, it's the presenters obligation to prove his theory with witnessed documented material, not pushed off to others to disprove.

I would also like proof that the average of 5 five shot groups (fired in one string) will group smaller than one 10 shot group.

In my shooting disapline, we shoot at between about 55,000 rpm and 92,000 rpm and our 1 and 200 yards group records are more than a 2 to 1 difference.

Frank

[Larry Gibson]

frnkeore

First things first, Larry, I have suggested the scientific blind test twice to prove your "theory" I'll do as you suggest AFTER you do what I have suggested.

Ok, send me 5,000 dollars and we'll build the rifle with 3 barrels to run your test. Show me where any manufacturer has a 200 yard test tunnel? All my research shows testing is done at shorter ranges or outside. Just another impossible "prove it this way" you got from we all know who.

In the sciencific world, it's the presenters obligation to prove his theory with witnessed documented material, not pushed off to others to disprove.


Absolutely correct. I have presented sufficient evidence to convince everyone but you and about 3 others. In the "scientific community" it then becomes the dissenters responsibility to disprove it. So you dissent; so prove the RPM threshold does not exist. There are some who still argue the world is flat even though it's proven otherwise..........

Five 5 shot groups vs one ten shot group is harder is your theory......."in the scientific community......." so the ball is in your court and you should now prove your own "theory". Additionally everyone but you seems to understand the difference of your theory has nothing to do with exceeding the RPM threshold because non of those groups exceeded the RPM threshold nor did none of the 10 shot groups they were compared to. Neither does all the groups the CBA shoots at "55,000 to 92,000 RPM".....and neither does the 2 to 1 difference.......

What matters is the difference of linear or non-linear expansion between 2 equal groups; one fired at 100 yards and the other fired at 200 yards. All the other esoteric figures and records of CBA matches you come up with mean nothing in that regards because they do not exceed the RPM threshold. Get it.....the loads have to exceed the RPM threshold for the effect of the RPM threshold to be measured.....not hard for anyone of real interest to understand. If you do not understand it then you simply don't want to and you are therefore just arguing for the sake of your heartburn with me, aren't you? Answer that one.

Larry Gibson

[singleshot]

I get two hits somewhere down range and even shot my truck once even though it was way out of the line of fire. -Nobade

So, Nobade, now you're just bragging and showing off! Do you expect us to believe you didn't mean to shoot your truck?

Reminds me of an episode of Beverly Hillbillies where they were having a shooting contest ricocheting shots off rocks and other things to hit targets like playing billiards. But even they couldn't predict the trajectory of a shredded boolit! :kidding:

[MBTcustom]

Larry, I have to ask, why do you hang so much on linear group expansion? I shot jacketed bullets for years before I finally made an honest man of myself and went 100% cast, and I have seen all manner of strange groups at different ranges.
Take Winnifred for instance (the beloved 300Winmag Remington 700) She shoots bigger MOA at 100 than she does at 200 with 165gr SGKs.
Seems like I remember reading that the british actually bragged about the fact that they shot better at longer range than the americans did?
Point is, it seems to me that depending on the boolit design and a host of other factors, you might just get varying MOA groups at varying distances as a matter of course even with a rifle that shoots perfectly.
I'm not sure that's the best data to prove (or disprove) the RPM theory with. No?
Just for the record, at this time, I completely agree with the RPM theory, but I don't think the cast boolits are limited to 140,000-160,000. I think that is completely dependant on the internal ballistics of a particular rifle/ammo combo.

[frnkeore]

Wrong again, Larry,
First, you don't have to use a tunnel, I suggested 10 ten shot groups from each barrel for reliable results. Second, I say put your money where your mouth is.

You brought up the 2 to one theory regarding groups and yardage, I was merely pointing out at under the best conditions (55,00 - 92,000), 2 to 1 is unreasonable when in the real world it's not so.

Match shooting IS the real world, not words in print or out of mouths. That's the specific reason that I present those results. Everything in match results are TOTALLY comfirmed! No, I think it's this way, no, I swear I did it better at home, no, I can't find the target to prove it, no nothing just comfirmed facts.

Lastly, I'm not arguing for the sake of argument, I don't have a "heartburn" for you, all I ask for is verified truth or at least "this is the way I think it works, you be the judge". Trying to defend something that isn't proven is impossible.

Put your money down and then get back with us.

Frank

[Larry Gibson]

Goodsteel

I'm not hanging on to linear expansion. Others have harped on and on about proof the RPM threshold exists and how do we know when a cast bullet has crossed the RPM threshold. If accuracy is going south through group enlargement of because of flyers (those are uncalled shots out of the group) then the easiest way to determine if it because the RPM threshold is crossed is to double the range, shoot and equal number of shot group (of a sufficient sample size) at each range and check for non-linear expansion of the group at the distant range. It's the proof 45 2.1, starmetal, gear and now frnkeore demand but can't accept. Nor can any of them conduct the simple test I suggest to prove it to themselves. Have you conducted that simple test to prove it to yourself? I know we're on the same page but best if you prove it to yourself.

I have put my money where my mouth is. I have purchased and use 9 rifles with scopes on the of which 7 are heavy barreled match/varmint rifles capable of extreme accuracy. I have purchased a M35P chronograph and an additional M43 Oehler PBL to measure velocity, TOF, BC, pressure and get a time/pressure curve. I have conducted several thorough and extensive test of the .223 with 7, 9, 12 and 14" twist barrels. I have conducted numerous and extensive tests of the .308W with 10, 12 and 14" twist barrels and I have conducted numerous and extensive testing of the 6.5 Swede with several different cast bullets at HV. All that not to mention all the other cast bullet shooting I have dome with CF rifles over the last 40+ years. I have thousands of dollars invested in not only rifles and casting equipment but in study and knowledge of ballistics. Now some one who can't even grasp the difference between match shooting (oh yeah, I have done my share of that...I have a Master NRA classification in HP and long range shooting, was a Class A IPSC competitor, won my share of small bore matches and even won a couple hunter BR matches.) and shooting a cast bullet until it crosses the RPM threshold and loses accuracy. He has incessantly argued with me on numerous threads on different subjects ever since I called him wrong on an unsafe suggestion he gave to another member. Look at his posts; has he done anything I suggested would prove the RPM threshold...no. Has he answered any of my questions....no. He just keeps up with CBA scores that have not crossed the RPM threshold and prove nothing. He can't understand that crossing the RPM threshold means accuracy is bad.....he seems to think I should shoot in CBA matches with loads that are inaccurate and prove what? So how do I answer such? I can't and I won't even try any longer because I have given him the answer on how to prove the RPM threshold exists several times. He won't do it, just like several others won't, because he and they know if they do they'll have the right answer and then how can they argue? Nope, I'm through with him as I have put my money down and I have gotten back to everyone.

Larry Gibson

[Larry Gibson]

Nobade

Great thread and an awesome rifle. If you have any questions or thoughts on what to test or what works please PM me as I'd love to discuss it with you. I've not made up my mind on the barrel twist for the 26" barrel goodsteel is going to put on a M98 Mauser for me and chamber it in 30x57. If that doesn't get me where I want I can always open it up to standard '06. I'm torn between the 14" twist and going to a 16" twist. Yes I know 45 2.1 thinks it is worthless as it won't handle "heavy bullets" but the 16" twist does fine with 170 gr cast in the 32 Win SPL so it should do fine with 170 gr of lighter cast bullets at higher velocity. I'm building mine as a coyote, deer and antelope rifle with cast bullets with a 500 yard max range in mind so heavier bullets than 170 gr aren't in the picture anyways. From the looks of your 500 yard shot groups on the steel targets I think I'm headed in the right direction. Again, beautiful rifle and well done on the loads and shooting. I'm out of this thread now. PM if you want or maybe we can start a new thread and not have it ruined?

Larry Gibson

[LynC2]

WOW! What was a very interesting thread started by my friend Nobade turned into a PZZING contest. I admit there was a lot of good information and theories postulated which I feel was great; but really do we have to shut down an excellent thread because we disagree with a difference of ideas and opinions? Personally I'd prefer to see it expanded and perhaps some more detailed information regarding loading data, etc. I can personally pump Nobade for information, but that doesn't help others looking for data and I am certain there are a lot of others that have pertinent information that would help us all.

[Nobade]

I got to go shooting for a bit with this rifle again today. Same RCBS 165 SIL, but loaded over a duplex charge of 4.7gr. IMR4227 + 58gr. WC857. This works better than the IMR4895 I was using by quite a bit. Still no chronograph, but it was really ripping them out there judging by the time it took to hit the hanging steel and how flat it shot. Only 2 inches (1 MOA) difference between 100yd and 200 yd zeros. But accuracy was improved quite a bit - I shot several 100 yd groups on paper that were in the 1/2 inch range and lots of hits touching each other. The slow ball powder does seem to be kinder to boolits than the much faster 4895, just like it does with paper patched ammo. I was sort of nervous duplexing this powder, but it responds very well to it. I certainly wouldn't try that with anything faster though, at least not in a cartridge case this large. Now I am looking forward to getting to enter this rifle in a highpower silhouette match and see how I can do with it against those pesky J-word shooters.

-Nobade

[Larry Gibson]

Outstanding!!!

The slow ball powder does seem to be kinder to boolits than the much faster 4895,

That is one of the key things (using a slower burning powder to lengthen the time pressure curve) to keeping the bullet balanced during acceleration.

Larry Gibson

[felix]

Go to 14 twist, Larry, because of the case of boolits you have or can make now with molds you already have. 16 twist will limit the boolit length too much when shooting past a hunnert. ... felix

[Larry Gibson]

Go to 14 twist, Larry, because of the case of boolits you have or can make now with molds you already have. 16 twist will limit the boolit length too much when shooting past a hunnert. ... felix

Frankly being "limited" to a choice of bullets is not really a concern as I have 3 bullets in mind; 311465, 311466 and the LBT 150 gr SP. The 16" twist will handle those very well at the 2700 - 2900+ fps (maybe even the magic 3000 fps mark?) range I expect to use them at. Note how well the 32 SPL handles the 170 gr cast at a sundry 2000 - 2200 fps......

And if I do want to use a heavier bullet it's not like I don't have enough 10" twist 30-06s around in the gun safe.......besides a 311299 is fully stable at 2440 fps from the 16" twist barrel. With the 30x57 or the '06 that is certainly quite probable with a 26" barrel. The 311041 is max stable at 2700 fps and minimally stable down at 515 fps. The 16" twist might not be quite as "limiting" as some think.

Larry Gibson

[Pat I.]

Go to 14 twist, Larry, because of the case of boolits you have or can make now with molds you already have. 16 twist will limit the boolit length too much when shooting past a hunnert. ... felix

I shoot a 17 and a friend of mine shoots an 18 so this isn't true. One of the bullets I'm using is .970 long and weighs 170 grs. I'm able to get 2550 fps with pretty good accuracy. Plenty good for 200 yds and beyond. You might have to order a new mould but that's the cost of doing business when you play with something new.

[NYBushBro]

For a second, I thought I was on the Swedish CM thread.... :-)

Seriously, after having thumbed through bits of this thread, I sure am glad that my Win 401 SL's have a 14" twist.
(32 SPL's and 35 REM's have a 16" twist... so are we talking J-word velocity - or at least heavy for caliber bullets - with them?)

Concerning the 14" twist, what would be an optimum bullet length that this twist will prove satisfactory? The reason I ask is that for a given cartridge, the LENGTH of the bullet is more associated with a particular twist then the WEIGHT of said bullet.

The reason I ask is that I have some .41 caliber bullets (240, 260 and 300 gr) that I would like to get to work in the .401 SL.

Glad I stumbled on this thread, as I have been considering getting a 98 Mauser re-bored for a 35 caliber cartridge, and there is a H&G #141 (300 gr., 1.2" bullet) that I would love to shoot in either a 9x57 or a Whelen (or a .358 like Paco). It's a honkin' big bullet.

(Please PM me so we don't hijack this thread. Thanks.)

[TXGunNut]

Wow, that's great! If you don't mind me asking; how in the world do you come up with that powder charge?

[Larry Gibson]

NYBushbro

PM sent.

Larry Gibson

[Nobade]

Wow, that's great! If you don't mind me asking; how in the world do you come up with that powder charge?

Well, I initially tried a compressed load of just the WC857 before I rebuilt the rifle. It gave low velocities and left lots of unburnt powder behind. So it was obvious to me that by itself it wasn't building enough pressure to operate properly. As for the 4227 part, I had the #3 rotor in my little dandy measure installed and that looked like about enough so I went with that, and added enough 857 to fill the case and make a tightly compressed load. Pretty scientific, eh?

-Nobade

[TXGunNut]

SWAG'ed it, nicely done! I think when you get the feel for a certain powder and cartridge those things come to you, nothing WA about it. I wouldn't know WC857 if you dropped an 8 lb keg of it on my head. OTOH I developed a Varget load for my 30-06 before there were published loads, the max load I came up with was just a few tenths of a grain north of the loads that were later published. Just worked up to it and stopped when everything felt right. That was a rare 30-06, most I've had don't like anything close to max.
Where do you think you are velocity-wise, 2300-2400?

[Outpost75]

lag time dupe deleted.

[Outpost75]

I've enjoyed reading this thread and have nothing to add except for all of you to re-read Larry's posts, then to dust off dust off your statics and dynamics textbook, review strength of materials, and then write a 1000-word summary explaining "hoop stress."

My best. 30-'06 cast bullet rifle WAS a 14" twist by Homer Culver wth barrel by P.J. Hart, chambered with a .337" neck on a Hart 1a heavy varmint action, ca. 1980s.

You guys have succeeded in reinventing the wheel. Thanks.

No longer have the Hart 1A, but do have a 14" twist Douglas with min. SAAMI chamber for my switch-barrel Sako A2 and I'm going to have to drag it out now for Larry. Should be fun!

[HARRYMPOPE]

[QUOTE=
You guys have succeeded in reinventing the wheel. Thanks.[/QUOTE]


Glad somebody said it!

[GabbyM]

I've enjoyed reading this thread and have nothing to add except for all of you to re-read Larry's posts, then to dust off dust off your statics and dynamics textbook, review strength of materials, and then write a 1000-word summary explaining "hoop stress."

My best. 30-'06 cast bullet rifle is a 14" twist by Homer Culver wth barrel by P.J. Hart, chambered with a .337" neck on a Hart 1a heavy varmint action, ca. 1980s.

You guys have succeeded in reinventing the wheel. Thanks.

I believe we all know that. Win 32 Special has been shooting it's 170 grain cast boolit fine with a 16 twist barrel. For a year or two.

Very few people building cast boolit specific 30-06. I love the 30-06 round. I can laod mine with 28 grains of Rx7 using 150 to 200 grain boolits and they all hit on target with reference to elevation directly tied to velocity change. It even shoots the 178 grain J bullet full power load with the same scope setting. 06 is a bullet pump. Wish I’d of had one forty years ago instead of the necked down 06’s.

[Larry Gibson]

Been like pulling teeth to get many to understand how RPM adversely affects accuracy at a certain level with cast bullets. Getting them to comprehend the best way to achieve HV accuracy with cast bullets is to slow down the RPM....via a slower twist barrel. Some still don't grasp the thought.......

Outpost

How about posting some accuracy results (with all the neat details of course) with your rifle?

Larry Gibson

[frank505]

try a 32 twist in a 45 colt available from green mountain barrels. Stabilizes my 360 Keith slug as far as I can see the hits........

[45 2.1]

I've enjoyed reading this thread and have nothing to add except for all of you to re-read Larry's posts, then to dust off dust off your statics and dynamics textbook, review strength of materials, and then write a 1000-word summary explaining "hoop stress."

My best. 30-'06 cast bullet rifle is a 14" twist by Homer Culver wth barrel by P.J. Hart, chambered with a .337" neck on a Hart 1a heavy varmint action, ca. 1980s.

You guys have succeeded in reinventing the wheel. Thanks.

Statics is a different course than Dynamics..... different textbooks and subject matter for those of you that don't know. You've listed a full time load for a year or more of college courses there if you include the background courses you would need to understand that subject matter. Been through that myself.


Glad somebody said it!

Yes, everybody here seems to be reinventing that old 160 year or so old wheel now. Mr. Whitworth did that for the British government in the mid 1800s also, so the basic idea has been around for quite a few generations with "testing" in each of them from other folks reinventing the wheel also. Now, a conclusion...... if it worked so well, then the firearms companies would be doing it.... and they aren't.... are they! The problem is a slower than normal twist is only useful in basic ranges of velocity for the bullet/boolit length used. Would Outpost, HARRYMPOPE or Pat I. care to tell us what they found as per boolit weight and velocity range they use AND the distance shot along with their thoughts on stability of the projectiles? I don't think you're going to see a 311299/314299 going at 1700 fps with any kind of accuracy in a 14 or slower twist. How 'bout it guys.........

[Pat I.]

I shouldn't but I will.

Why in the world would anyone build a .30 caliber rifle with a 14 or slower rate twist to shoot a 311299 at 1700 fps? Kind of defeating the purpose isn't it? And the reason factories choose the twists they do is because they have to work for "everyman" and obviously they do it well enough to stay in business.

I don't know why you have such a problem with rifles being twist limited in the accuracy department. It's a well known fact in both the cast and jacketed bullet world. From personal experience and what I've read on here you've had more than ample opportunity to prove people that have actual experience using different twist barrels wrong with a witnessed demonstration but never have for some reason. It's easy to talk on a forum about special loading techniques and uber velocities with fast twists but demonstrating it in front of a live audience is the only way you'll ever prove, to me at least, that it isn't exactly what I said earlier in this sentence.... talk on a forum. Maybe you just like to argue which is perfectly alright with me but at least argue from a position of strength and showing up to a shoot with nothing to back up the claims you've been making for God knows how long makes your arguments look pretty weak.

[45 2.1]

Pat, that is not the question you were asked about. If you can't relate what you learned about slow twist barrels, then please refrain from tirades. Basically, the idea that slow twist barrels are twist limited and not for general all around use IS what needs to be established so the less knowledgeable people know not to spend money on something that has been made to appear a cure-all for their problems. What they are capable of along with the boolit weight and velocity range they work in would be a great help to everybody here. You seem to say that with numerous posts, but won't say. Why not if you have the experience and knowledge?

For the record, the CBA does not shoot matches I'm interested in and are never likely to given the benchrest type nature of those matches... plus, ALL the individuals who so aptly wanted to see, had a dog in the fight. One could hardly be objective in such an atmosphere such as was provided by the rhetoric espoused or expect an honest report of the results given that same rhetoric without uninvolved witnesses of standing here watching.

[Outpost75]

Been like pulling teeth to get many to understand how RPM adversely affects accuracy at a certain level with cast bullets. Getting them to comprehend the best way to achieve HV accuracy with cast bullets is to slow down the RPM....via a slower twist barrel. Some still don't grasp the thought.......

Outpost

How about posting some accuracy results (with all the neat details of course) with your rifle?

Larry Gibson

Would if I could find the logs, but they were lost between one of a dozen moves since then. Sold the Hart 1A, but I know where it is and hopefully the current owner still has that barrel. As I recall we got very acceptable results using a 190-gr. Hoch nose-pour cast 50-50 monotype and wheelweights, quenched, with the old M&N lube and 54 grs. of W760, not half minute, but consistently sub-minute to 200 yards. Velocity was about 2450 fps.

I currently have a 14" twist Douglas .30-'06 barrel with ordinary SAAMI chamber for my switch-barrel Sako A2, I'll be working up some full-charge loads with that in the spring using the HM2.312-160-5 bullets from the group buy, so wee how it does with loads heavy enough to cycle my M1.

[waco]

I need a few beers after reading all of this...........

My head hurts!

98.4% of all this discussion went right over the top of my ginger head!

I do love you guys though! :drinks:

[Pat I.]

Pat, that is not the question you were asked about. If you can't relate what you learned about slow twist barrels, then please refrain from tirades. Basically, the idea that slow twist barrels are twist limited and not for general all around use IS what needs to be established so the less knowledgeable people know not to spend money on something that has been made to appear a cure-all for their problems. What they are capable of along with the boolit weight and velocity range they work in would be a great help to everybody here. You seem to say that with numerous posts, but won't say. Why not if you have the experience and knowledge?

For the record, the CBA does not shoot matches I'm interested in and are never likely to given the benchrest type nature of those matches... plus, ALL the individuals who so aptly wanted to see, had a dog in the fight. One could hardly be objective in such an atmosphere such as was provided by the rhetoric espoused or expect an honest report of the results given that same rhetoric without uninvolved witnesses of standing here watching.

I'd hardly consider what I wrote a tirade and I do feel I answered your questions. Who decides what's "general all around use"? I'd be willing to bet at least 95% of the people shooting cast bullets never shoot past 200 yards and probably 99% never shoot past 100. For the vast majority of cast bullet riflemen out there an under an inch 170 gr bullet in a 16 twist would be the perfect fast general use combination. It's not that I can't relate what I've learned about slow twist barrels it's that you can't or won't understand it for some unknown reason. Your answer is always some obscure "if you really know what your doing" thing while ignoring the advise and knowledge gained and willingly shared by people that do know what they're doing and have actually done it. I'll repeat what I believe and have said at least 100 times about .30 caliber velocity and twist rate one more time. Starting with a 10 twist you're going to find your best accuracy at around 1850 fps. For every inch slower twist you can add about 100 fps or so. I've proven it to myself with an assortment of .30 caliber match barrels and study of the CBA match results backs up my personal findings.

I don't buy your "dog in the fight" argument. What would anyone possibly have to gain by lying about how someone shot or the velocity they got. The people I was referring to that had a chance to see what would happen were friends of yours at the time and when I offered to come down and witness your claims I offered to bring my chronograph and a camera so there'd be no hanky panky. I also offered to let you bring unbiased witnesses who had "no dog in this fight". This isn't a me against you thing. It's all about being truthful and realistic about what cast bullets can do. The old "your methodology is wrong" thing can only work for so long before someone is going to want more than words on a web page as proof. Why keep trying to convince someone that they're doing something wrong when in reality they're trying to do something that ain't gonna work. Bottom line for everyone is keep the 10 twist .30s around 1800 fps or so and listen to the guys that have actual experience and you'll live long and prosper. Try to get the velocities with accuracy claimed by some proven by none and you'll have nothing but frustration. I also wish people would stop calling what we're talking about " Larry's theory" because it's a fact and known about long before Larry talked about it here.

[geargnasher]

I've enjoyed reading this thread and have nothing to add except for all of you to re-read Larry's posts, then to dust off dust off your statics and dynamics textbook, review strength of materials, and then write a 1000-word summary explaining "hoop stress."

My best. 30-'06 cast bullet rifle WAS a 14" twist by Homer Culver wth barrel by P.J. Hart, chambered with a .337" neck on a Hart 1a heavy varmint action, ca. 1980s.

You guys have succeeded in reinventing the wheel. Thanks.

No longer have the Hart 1A, but do have a 14" twist Douglas with min. SAAMI chamber for my switch-barrel Sako A2 and I'm going to have to drag it out now for Larry. Should be fun!

If you go to the trouble and expense of a reasonably dimensioned, quality barrel, then take the equivalent hour-load of the classes you suggest in Cast Boolits 411 and 412, with a review of Strength of Materials, you may find that your twist rate is irrelevant provided it achieves minimal stabilization of the boolit. Problem is, there may only be two or three current forum members who have bothered to do that.

Gear

[btroj]

No statics or dynamics for me. Not interested in revisiting that much math.

[geargnasher]

All I remember is that the indefinite integral of e to the power of [x] equals the function of f times u to the [n]th power. Basic calculus.

Gear

[Wayne S]

Outpost

How about posting some accuracy results (with all the neat details of course) with your rifle?

Larry Gibson YES, pictures, we have enough words

[eck0313]

Char-Gar brought up a good point several posts ago. The 14 twist is great for bullets in the same weight and length over diameter range as a Sierra 168. Much heavier, or longer, and you'll find it won't shoot as well.

Now many years ago I shot Hunter Class benchrest with a blueprinted Rem 700 and a 14 twist barrel in .308. It was a legitimate .25 MOA rifle with 168s and 40.5 to 41.5 H4895. Heavier bullets did not fare as well. At the time, there were no lighter .30 bullets that would shoot as well as the Sierra 168.

Enjoy your rifle - or rather continue to enjoy it!

[45 2.1]

If you go to the trouble and expense of a reasonably dimensioned, quality barrel, then take the equivalent hour-load of the classes you suggest in Cast Boolits 411 and 412, with a review of Strength of Materials, you may find that your twist rate is irrelevant provided it achieves minimal stabilization of the boolit. Problem is, there may only be two or three current forum members who have bothered to do that.

Gear

A good true point........ a lot of people think they have achieved it all, even among some of the benchrest crowd. That would be a false assumption.

[Larry Gibson]

Would if I could find the logs, but they were lost between one of a dozen moves since then. Sold the Hart 1A, but I know where it is and hopefully the current owner still has that barrel. As I recall we got very acceptable results using a 190-gr. Hoch nose-pour cast 50-50 monotype and wheelweights, quenched, with the old M&N lube and 54 grs. of W760, not half minute, but consistently sub-minute to 200 yards. Velocity was about 2450 fps.

I currently have a 14" twist Douglas .30-'06 barrel with ordinary SAAMI chamber for my switch-barrel Sako A2, I'll be working up some full-charge loads with that in the spring using the HM2.312-160-5 bullets from the group buy, so wee how it does with loads heavy enough to cycle my M1.

Understand the "losing" of stuff in moves.......

Awesome on the new rifle, looking forward to reports from you.

Larry Gibson

[Larry Gibson]

As I recall we got very acceptable results using a 190-gr. Hoch nose-pour cast 50-50 monotype and wheelweights, quenched, with the old M&N lube and 54 grs. of W760, not half minute, but consistently sub-minute to 200 yards. Velocity was about 2450 fps.

Perhaps 45 2.1 should grab a clue from the above. Seems he continually chooses to ignore the success with the 311041, 311291 and the 311299 (170 - 200 gr cast bullets) that has been reported here by myself and a couple others using 14" twist '08s and '06s. He keeps harping on "lack of versatility" of the slower twists but has failed to take my advice and get one and then talk the talk.

eck0313

Bullet stability, for a given twist, is dependent on bullet length not on bullet weight as some here seem to think. Your example of the 168 MKs in the 14" twist illustrates that point exactly. The 168 MKs are 1.248" (+/_) and obviously shoot extremely well in your 14" twist rifle. They do min my 14" twist rifle also. Heavier match j bullets are of course longer, especially the VLD type, and do not shoot as well because they are minimally stabilized. However, we ARE talking cast bullets here, are we not? The fact is the heavy (200 gr) 311299 w/GC is 1.196" (+/-) long. That is shorter than the 168 MK and is the reason the 14" twist stabilizes that heavy 311299 cast bullet quite well.

We all know that is contrary to 45 2.1's argument and contrary to his and geargnasher's very self stated schooling. But it is fact that a 30 cal barrel with a 14" twist chambered in .308W or '06 (or similar cartridges) will indeed shoot the "heavier" cast bullets of 160 - 200 gr very well indeed, a ballistic fact that is easily proven.

Larry Gibson

[Larry Gibson]

"I also wish people would stop calling what we're talking about " Larry's theory" because it's a fact and known about long before Larry talked about it here."

Yup, not my "theory" at all. I explained that in the very beginning and who knows how many times since.........but the mentioned "two or three current forum members" apparently haven't comprehended that or the historical facst or the laws of physics/ballistics.....even though they pretend that copying a calculi's equation is understanding it.............

Can we get back to the OPs intent for this thread instead of the usual BS? So ok, "two or three current forum members" don't buy off on the RPM threshold concept......how about just letting us that do have a peaceful and decent discussion? The "two or three current forum members" could start their own thread and actually prove the RPM theory/concept wrong with facts, could they not? Would be refreshing to carry on a conversation about this w/o the bickering and simply stick with proven facts and science.

Larry Gibson

[nanuk]

All I remember is that the indefinite integral of e to the power of [x] equals the function of f times u to the [n]th power. Basic calculus.

Gear

I refer the Jethro Bodine method, where 1+1=3

[MBTcustom]

"I also wish people would stop calling what we're talking about " Larry's theory" because it's a fact and known about long before Larry talked about it here."

Yup, not my "theory" at all. I explained that in the very beginning and who knows how many times since.........but the mentioned "two or three current forum members" apparently haven't comprehended that or the historical facst or the laws of physics/ballistics.....even though they pretend that copying a calculi's equation is understanding it.............

Can we get back to the OPs intent for this thread instead of the usual BS? So ok, "two or three current forum members" don't buy off on the RPM threshold concept......how about just letting us that do have a peaceful and decent discussion? The "two or three current forum members" could start their own thread and actually prove the RPM theory/concept wrong with facts, could they not? Would be refreshing to carry on a conversation about this w/o the bickering and simply stick with proven facts and science.

Larry Gibson

It takes two Larry.
I see folks on both sides of the fence doin a lot of postulating and not posting too many pictures of personal groups.
I for one, am still on the fence about the whole RPM thing. No offense to you, but I respectfully disagree as I believe the damage done to the boolit in the first inch of the barrel is the limiting factor, and not the RPM per se'.
I am going to be doing my own experiments on this issue in the spring, and when I'm sure I have something to post, I'm going to open this can of worms myself in a dedicated thread.
I will give you fair warning, I will delete any jab thrown at another member, as well as any post that does not have pertinent information in it. I want to find the truth about this once and for all, and I am not biased either way. I have bent over backwards to help the good people of this forum to learn and to grow in their knowledge, and this constant fighting about a vague issue is juvenile.
For the record, I consider knowledgeable people on both sides of this issue as personal friends, and I refuse to turn back on that over an issue like this.
We are scientists. Rather than beating each other up over an issue that is hard to prove we should be putting our heads together and finding out the truth of it.
I would like to see that become a reality, and I'm willing to go the extra mile with each of you great fellers as I have great respect for your abilities (despite your individual prickly personalities).
We should have been past this a long time ago, and 2014 is going to be the year if you care to help me and all the other posters figure it out (speaking to Larry, Bob, and all of their followers/cohorts).
I desperately want to know the truth of his issue, to the satisfaction of all the evidence, and so do a lot of other people. Problem is, I'm not willing to accept a big assumption, and ignore a big piece of evidence before moving forward, therefore, I scrutinize everything.
I would like to ask all who read this to watch for the thread I will start, and please prepare to experiment, prepare to learn, and please throw out the presupposed ideas, and help us learn.
I hope that when all the smoke clears, everyone will still be members here, and the thread will be a reference for future posters.

Now, that being said, please move on, and let Nobade enjoy his new rifle.

Nobade, I apologize for this. Congratulations on a good rifle! I'm going to have to try your duplex load someday.

[308w]

I have sat here this morning and read this entire thread. I don't have a side that I am on, I deferr to the fact that the posters here are far more knowledgeable than me and have enjoyed and learned quite a bit from the thread.

The constant in this thread that I see is the less damaged or altered the boolit is when it leaves the barrel, the more likely you will find accuracy at higer velocities.

The fact that pp boolits seem to be able to shoot well with higher velocities, than conventional grooved lead, and the results from the gentleman who got pretty dang good results from the saboted .22's at 4000 fps plus seem to agree with what I see. I mean I would think that the grooved boolits would be the most damaged/altered and the saboted the least and the pp falling in between the two.

With that said, could it be that finding a method of rifleing that damaged the projectile less, would also lead to higher velocities with accuracy?
A very interesting experiment would be rifles of the same twist but with different types of rifleing, micro groove, hexagonal, etc. or maybe even looking to which style would be the most cast friendly.

Just my 2 cents, Thanks to all for some very good and insightful information.

[Larry Gibson]

Goodsteel

Jab all you want but you might consider the difference between interior ballistics (which you seem stuck on) and what happens to the bullet in flight (that's exterior ballistics). You are correct, it does "take two". Go back through the thread and see who started the jabs first.....but that doesn't really matter as I will jab back when jabbed....seems only fair enough......btw; do you think you are one of the "two or three current forum members"? If you read that correctly the jab was at you as well as I and everyone else here except the "two or three current forum members".

I for one, am still on the fence about the whole RPM thing. No offense to you, but I respectfully disagree as I believe the damage done to the boolit in the first inch of the barrel is the limiting factor, and not the RPM per se'.

We all strive to launch that perfect bullet. But do we? No we don't and thus it is what occurs to the imperfect cast bullet in flight (that's the exterior ballistics) that acts upon the imperfection to the cast bullet that occur during casting, loading and inside the barrel (the internal ballistics part). Were the adverse affects of RPM (actually centrifugal force) not there in flight we could shoot the most unbalanced bullets and they would be just as accurate as the perfectly balanced bullets all other things being equal.

You might also consider the fact that even the "two or three current forum members" agree that slowing down the time/pressure curve is necessary for HV cast bullet loads. A study of time/pressure curves will show you the acceleration to the bullet, hence potential damage to the bullet, occurs well beyond the first inch of travel in the barrel.

You want the truth once and for all? Then simply run the test I have outlined to you and others numerous times. if you forget I can easily repost as the test is simple and easy. Actually you have probably (from you other posts) already ran the test but simply didn't realize it. Have you ever worked up a cast bullet load with a 9.5 - 10" twist barrel? As you increased the powder charge at some load the accuracy began to go with a flyer or two. Then at a load above that accuracy totally went south. If you chronographed those loads or where accuracy remained good and did the math I'll bet the RPM was below 140,000. If I am wrong then say so and give the details?

Larry Gibson

I'm done with this thread as it's getting out of hand. If you want to comment to me PM me.

[Love Life]

Tim,

If you have a way to do it, you can mount my 308 barrel and use that for your testing. It is a 1 in12, chrome lined, and is sub MOA out to 700 yds all day long. It can't be rechambered or anything, but you can use it for your tests. It is a known accurate barrel.

[MBTcustom]

Will do Larry.

Thanks for the offer LL, but I would have to have another FN in order to properly utilize that barrel. Besides, I'm building a rifle for these tests that has a 1-11.5 twist. I just wish I could get a few other barrels for it in different twists and calibers. Who knows, maybe I'll come into enough money to run the full spectrum. For now though, I'm going with 308.