RPM Threshold barrel twist/velocity chart

[btroj]

Well, that answers that. Thanks Dutch and Mike.

Tim, you need to listen to Mike. You are way too worked up over this. Some don't post here because they don't want to. That doesn't make them evil, they just may not care. Just because a person doesn't share everything doesn't make what they did impossible or unachievable. Like Mike said, not everyone is a teacher. We also know a few aren't good at spoon feeding people.

The info is out there. Do the research. Learn.

Yes, a poorly balanced bullet will be affected by higher rpm. Any spinning load requires better balancing as the rpm goes up. A washing machine, tire, centrifuge, lathe, or whatever. The answer lies not in limiting how fast we spin things, it lies in how to better balance the load we are spinning.


We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too.

I wasn't alive for this speech Tim. Neither were you but let it be your guide. Don't do this because it is easy, do it because it is difficult. Doing the difficult things in life are what give us meaning. The difficult things are what give us purpose, they are the things that make us learn, grow, and push the envelope.

larry has given us a hurdle. It is now up to each of us to decide if we see a hurdle or a barrier. We can either learn to leap over it or we can be held back because of it.

[MBTcustom]

Your right, I am worked up over this because it's tearing down my favorite forum.
I never said anything was impossible or unachievable. I have a lot of faith in the human spirit and our ability to understand science, but I also realize that in any setting, you can spend years getting nowhere (like we have on this issue) if your research is based more on disproving someone else's research and fighting over who's righter, than pushing for your own viewpoint and then trying to see where it fits in the puzzle.

I'm only trying to help people to see the foolishness of fighting over different points of view, and trying to ram them into the same bottle.
There will come a day that we can take an all encompassing look at the HS castboolit issue, but for the moment, we need to divide and concur.

Its like looking into a dark place and trying to see the landscape in front of you. Larry illuminated a very specific piece of that landscape and instead of everybody shining their flashlight at different spots so that we might get a whole picture, lots of effort has been expended to snuff out his light because it doesn't encompass the whole panorama.

Dutch, thank you for that amazing post, but I wish it was a thread instead of a post in the middle of an RPMTH discussion.

To the rest of you, please, if you disagree with the OP, go start your own threads on what your research is telling you and leave this viewpoint out of it, and stay out of this discussion. I will defend your viewpoint from being attacked, squelched, subverted, or destroyed with the same fervor, but not if your whole basis for research is to disprove something that someone else has done. That's not science. That's using something that looks like science as a weapon to beat people over the head with. If your research is based on your rifles and your point of view, and is honestly looking for truth (like this thread started, then I want to hear everything you have to say, and so do a lot of other people.

If everybody did this, then I think we would get where we are trying to go much faster and happier.

[btroj]

Rpm arguing, disagreement, and the like isn't what is tearing down this forum. That is an entirely different problem, call it forum evolution.

larry and others have been arguing over this for a decade or more. This is hardly a new battle.

Any time you get people who are deeply engaged in an activity there will be heated disputes. Thinking people often don't agree. If they do then someone isn't thinking.

A constant focus on the issues that separate us is far more divisive than the issue itself. Is the fact others insist I agree with the theory any worse than my refusal to do so? Singling out naysayers as trolling leprechauns doesn't do anything to solve the problem does it?

[Newtire]

I'm glad to see that the arguments about spelling and other unrelated nit-picking has come to a halt and things have gotten more civil and to the point of the topic. Somehow, I keep seeing how a spinning top acts as it slows down and begins it's "death wobble" just before it finally starts walking all over the floor and crashes into the nearest wall. It helps me understand that there seems to be a certain point where it loses stability but it never regains it once it begins that wobble and is slowing down. I couldn't explain it but know it happens because I can see it. That's what I like about this experiment, the results are visible.

[Eutectic]

We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win, and the others, too.

I wasn't alive for this speech Tim. Neither were you but let it be your guide. Don't do this because it is easy, do it because it is difficult. Doing the difficult things in life are what give us meaning. The difficult things are what give us purpose, they are the things that make us learn, grow, and push the envelope.

larry has given us a hurdle. It is now up to each of us to decide if we see a hurdle or a barrier. We can either learn to leap over it or we can be held back because of it.

Great post Brad! Thank you for it!

I want to share a couple thoughts.....

WW2 was just over and I was in grade school. I was already a shooting 'nut' and already casting boolits! Under the strict eye of my father I might add. We shot with a guy I'll call 'Benny' ... Even as a kid I saw his arrogance and opinionated nature. My father like him and I listened to their conversations quietly and learned.
A few years later I went to work for a company that 'Benny' worked for as well. It those days companies had enough talent on board to train their employees in a college like atmosphere.... 'Benny' taught me metallurgy... He was the most arrogant person I had ever met at that time of my younger life. But he knew metal! Did he ever! He is now still, the smartest man on metallurgy I have ever known. 'Benny' has been dead for many years now.... a sad part of growing old. But he left me with a philosophy about life... one worth sharing.... "One should tolerate extreme arrogance if vast knowledge is being offered.... Yet extreme arrogance without knowledge can sound like a clanging bell!"

A gathering of vast knowledge such as we have on 'Cast Boolits' could be compared to a piece of hardened steel. It is strong and it won't bend! When you work to reshape it, you need to grind it... When you do sparks will fly! That's just how it is! You don't anneal the piece to more easily shape it without sparks..... IT MAY NEVER BE THE SAME AGAIN! (Attn: Mods)

I have supervised many brilliant people over the years... Brilliant people don't like to be micro-managed.. I've found it better to 'drop' a few hints and then let them 'take root' in their own brilliant mind... You see, people can't (or won't) tolerate a 'Benny' anymore.... It's sad for an old guy to see...

This site to survive, cannot be turned into a flock of sheep. Shepards are needed. The best of sheep will fail without them.
Moderators...... Let the sparks fly within reason! Political correctness has run amok in these times and shouldn't be the primary concern here at 'Cast Boolits' for us to survive. Some of my best friends have ground sparks from me and visa-versa......

You see, I did hear the speech Brad related to. In fact I was married and had a child. Old people have a wealth of knowledge even if their delivery is sometimes misunderstood.

Eutectic

[Larry Gibson]

Dutche4122's post settles what?

What you see in his post is exactly what I say can be done; push the RPM threshold up. He has used a good rifle with a good bullet cast of a non- ternary alloy. He has strengthened that bullet over the Ternary alloy......get it!

357amximum says in his post Dutch's accuracy was "about moa". Dutch says it is a documented 2.5 - 3 moa based on an actual target with only one load and only with a single 5 shot group. How many of you have gone out one day and shot the proverbial "eureka" very small group with a load, gone home and loaded up some more and then found out they really shot into much larger groups? I dare say all of you have. One 5 shot group is a very poor indication of actual accuracy potential.

I've also watched a lot of rocks and other things get shot at through binoculars and spotting scopes upwards of 25+ power. What we "think" is 2 -3" most often is a lot larger. How many shots hit the rock? Did any miss? In this case it was 'thought" the load to be "about" moa capable when, with insufficient sample size, it might have been, on an actual target, 2.5 to 3moa capable....maybe. Bit of a discrepancy in what was "thought"? We need to have sufficient data such as targets at sufficient ranges shot with sufficient shot groups to "settle" this. What we "thought" just doesn't settle anything.

I've no problem with Dutch's report, he is telling it as it was. But are we making assumptions based on insufficient data/results? Too many times we have made erroneous conclusions based on insufficient data. Until Dutch puts that load on paper at 100, 200 and perhaps even 300 yards with 10 shot groups we really won't know and neither will he.

So, btroj, what Dutch's post really "settles" is one way to push the RPM threshold up; harden the bullets by adding babbitt and heat treat/WQ. That is just as I have said many, many times as one way to push the RPM Threshold. But still, we don't know if Dutch's load really pushed the RPM Threshold simply because Dutch's test was not conclusive based on sufficient data. You went to great lengths explaining how you'd need a 100+ trips to the range, 200+ load combinations and 1000+ bullets to figure it out. But now you say Dutch with one inconclusive five shot group with one load, with just over 100 rounds (only 5 put on target) and then busting rocks with the rest "settles it"? Are you serious?

Look at the target below that has exceeded the RPM threshold by as much as Dutch's load. The 311291 was cast of the ternary alloy and was pushed at 2515 fps by 4895. Note out of 10 shots which gives the real picture of the accuracy potential there are 5 shots within 4" of each other at 200 yards. Those certainly would have been rock bustin' shots with a sight adjust too, wouldn't they? If I had only shot those 5 shots I might have come to the erroneous conclusion the RPM threshold was bunk too. With sufficient data (sample size of 10 shots) the truth emerges as we see the actual accuracy potential of 14.5" at 200 yards. I can show you many examples BTW including a MP 30-180 at 2509 fps cast of the same alloy as Dutch used. There were 6 of the 10 shots in that target which went into 3.5" at 200 yards. Problem was the other 4 shots stretched the actually accuracy to 11.5" for the sufficient sample group of 10 shots. That was out of my 10" twist '06 test rifle BTW. You might study "random selection" and "random dispersion" to understand why a sufficient sample size is necessary for surety of a conclusion. Surety of conclusion trumps "what we thought" every time.

Again, I have no problem with Dutch's post. It is quite interesting, informative and at least contains details on what he has actually done (not what someone else has done, especially as taken of match results where we really don't know the details). Realizing that the 2.5 - 3 assumed moa may be "acceptable U.S. Ordinance accuracy standards" at 100 yards but in the case with HV cast bullets does it hold that accuracy potential as the range increases? It may indeed prove very interesting if he can follow up with 10 shot groups at 100, 200 and 300 yards? Is the group expansion going to be linear of non linear? The answer found there would "settle it".

Larry Gibson

Attachment 108885

[Newtire]

An experiment like this one could take forever if you really think about it. It does work if everyone puts in a little bit of factual stuff. It's all useful as long as it's based on fact. Thanks again Larry and all you other guys with facts to share.

Now, we need someone to start a thread on rifles using gain-twist. I always thought that would be the way to go with cast. Only one I can think of that used gain-twist, aside from a few muzzle-loaders was the Carcano. It's gotta be someone with more money than I have!

[dtknowles]

357maximum is way to kind.

My rifle is a CMP Greek return Remington made 03A3 produced in May, 1943; with a brand new (in the wrapper & cosmo'd when I bought it) Remington made July of 1943 two groove replacement barrel. Barrel was installed by Badgeredd. As of this date the barrel has had only 103 rounds fired through it of the following load and no other:

Bullet Design: RCBS 30-180-SP (Late version, bore riding nose)
Actual weight lubed & checked: 190 grains

Cast of an alloy that is: (according to Badgeredd's alloy calculator)

92.35% Pure lead and other trace elements
3.73% Tin
3.5% Antimony
.22% Copper
.20% Arsenic

(Note: This is a copper enhanced alloy, and not the type of alloy that the OP used in the testing he has presented in this thread)

.........Bullets were water dropped from the mold into a five gallon water bucket. They were allowed to stabilize for two weeks, BHN was 28, sized/checked to .310" diameter and lubed with MML + 5% Soap. My mold casts a bullet nose that is .302" diameter using the above alloy from my mold.

The load itself is as follows: (loaded and shot as projected in Quickload)

46 grains of IMR-3031

CCI #200 Large Rifle Primer

54,000 psi / 100% powder burn / muzzle pressure = 7,849 psi

5 shot average over the chronograph is 2,510 fps. I was hoping to match the U.S. MkI ball load which was a 175 grn FMJ Spitzer at 2,600 fps. However, given the accuracy potential this load is showing I'm not going to quibble over 90 fps, especially since my boolit is 15 grains heavier..........dtknowles -

Right off the bat I will tell you this. Bullet fit is king. Also, my rifle has a 24" barrel and yours has a 22" barrel. I believe, based on my experience, that keeping muzzle pressures below 8,000 psi is very important for even usable accuracy. Your barrel will produce higher muzzle pressures than mine with the same load due to the fact that it is shorter. Find a bullet in the 200-210 grain weight range when cast out of this alloy that fits your rifle properly when chambered. Start out at 43 grains of 3031 and work up. If you have the alloy, lube, and fit right I think you could find a good load.

Thanks Matt

This looks like something I could use. I might try this alloy in my 30 BR. too.

Tim

[dtknowles]

........... Standard chambers, just won't cut it! The neck, freebore and leade angle are paramount when it comes to accurate cast bullet shooting, whether it's slow, medium or HV.

In closing, let me say again......... If one person can do something, reliably, then ANY other person can do that same thing! This is not magic, it's knowing how to put the whole package together.

May, 2014 Charlotte, NC

Galindo, Adolph, Class, UnP - Cartridge 30BR - Barrel, Lilja 22" lg, 8 twist
Scope, Leupold 40x - Weight, 22Lb. - Bullet, LBT 180 sp - Alloy, Lino - Nose .304, Base .310
Primer, Fed 205m - Powder Chg, 28.5, Varget - Vel 2100 (189,000 RPM)

Galindo, Adolph UnP 197 8x 100 yd, 193 2x 200 yd, 100/200 Agg 390 10x

Galindo, AdolphUnP 5 shot group, 0.469 100 yd, 200 yd,1.807 100/200 MOA 0.686

Galindo, AdolphUnP 10 shot group, 0.951 100 yd, 3.232 200 yd, 100/200 MOA 1.283

While all the examples are very good shooting, better than any that I have shot with cast bullets none of them are over 2200 fps and the point of this thread is to get higher velocity. Only one was over the 160,000 RPM which is where I think Larry has established we have pushed the Threshold. Adolph's example that I retained in the quote demonstrates exactly what Larry has demonstrated with his testing. You can see he is clearly over the 160,000 RPM at 189,000 RPM and his 200 yard groups are more than 3 times larger than his 100 yard groups indicating non-linear dispersion. Now maybe if he used Matt's hard alloy with copper and water dropped, his 200 yard groups would shrink.

Thanks for posting those data. I hope to shoot like those guy some day.

Tim

[Eutectic]

Now, we need someone to start a thread on rifles using gain-twist. I always thought that would be the way to go with cast. Only one I can think of that used gain-twist, aside from a few muzzle-loaders was the Carcano. It's gotta be someone with more money than I have!

I think this is a good idea too. dtknowles has also mentioned it in regards to this thread.

I would like to see if gain twist could raise this RPM hurdle we are pursuing in this thread.

Harry Pope did some gain twist barrels many years ago and he may have forgotten more than we all know about rifling a barrel for cast boolits.

Heck, I think Pope's rifling configuration alone might raise the RPM hurdle.

Gain twist will 'mess' with engravings on our boolit? But it's down the bore with pressures and torque lower and still may pass the test; even raise the bar.

Eutectic

[Larry Gibson]

A test with a gain twist would probably prove interesting but what should the final bullet rotation be?

Since we already know we shoot higher velocity in slower twist barrels with cast bullets why bother with the gain twist? Why not just use the slower twist?

Larry Gibson

[MBTcustom]

A test with a gain twist would probably prove interesting but what should the final bullet rotation be?

Since we already know we shoot higher velocity in slower twist barrels with cast bullets why bother with the gain twist? Why not just use the slower twist?

Larry Gibson

In theory, because the reason for using a slow twist is so that the boolit is damaged less during launch. Ie. you can push up the RPMTH by delivering a less damaged boolit to the crown.
The big expensive question is: Which damages the boolit less? a 16 twist, or a 15-10 twist?
My money's on the 16 twist, but we'll never know for sure until somebody pony's up some serious cash.
Seems I read somewhere that the gain twist was tried and the results were demoralizing, but I can't remember which book I read that in.....

[357maximum]

Your right, I am worked up over this because it's tearing down my favorite forum...........
To the rest of you, please, if you disagree with the OP, go start your own threads on what your research is telling you and leave this viewpoint out of it, and stay out of this discussion.

If you think for one minute that true heated/opinionated discussions BASED ON EXPERIENCE are what is bringing this forum to it's knees you could not be more wrong in my opinion. Look around in the staff discussions (I cannot provide a link as I no longer have access to that info) and find where I nominated Mr. Gibson for the Golden Boolit Award back when I was a mod......heated/opinionated discussions are what used to drive this forum to the truth and also towards the advancement of the common good. A mod taking sides and snuffing out the other viewpoint(s) is not gonna help........the problems this forum face have ZERO to do with heated discussions and opposing ways of interpreting the same info. Further thoughts by me are not wanted here......I can live with that.....so my final thought.........just because someone says this is the way, does not mean he is right...or wrong.....anything is possible with cast if you seek it....you may fall face down in the mud trying, but you will get farther swinging for the fence........ is all I got to say...good day/good week/good life/goodbye.

[MBTcustom]

If you think for one minute that true heated/opinionated discussions BASED ON EXPERIENCE are what is bringing this forum to it's knees you could not be more wrong in my opinion. Look around in the staff discussions (I cannot provide a link as I no longer have access to that info) and find where I nominated Mr. Gibson for the Golden Boolit Award back when I was a mod......heated/opinionated discussions are what used to drive this forum to the truth and also towards the advancement of the common good. A mod taking sides and snuffing out the other viewpoint(s) is not gonna help........the problems this forum face have ZERO to do with heated discussions and opposing ways of interpreting the same info. Further thoughts by me are not wanted here......I can live with that.....so my final thought.........just because someone says this is the way, does not mean he is right...or wrong.....anything is possible with cast if you seek it....you may fall face down in the mud trying, but you will get farther swinging for the fence........ is all I got to say...good day/good week/good life/goodbye.

You don't understand.
I'm not trying to snuff anyone's opinion out. Unlike the people who refused to teach me anything more about shooting HS cast lead unless I BAN LARRY GIBSON FOR NO REASON WHICH I REFUSED TO DO!!!!
talk about snuffing out information! That's about as low/underhanded as you can get, and why I am so very angry!

That's why I'm doing what I am doing! Even after all that, I want to hear all the sides, but this has gone beyond heated discussions online here.

Larry even offered in good faith to meet one member while he was in that members state and was turned down flat like he was scum.
That's not even getting into the death threats.
No, I'm not making any of this up. I have emails and phone conversations to back up what I am saying.

DO NOT accuse me of trying to silence anyone. I'm just trying to hear all sides and get people to quit acting like this, and if you think it is not having a negative effect on the forum, you are dead wrong. No one should have to endure that level of hatred for posting their opinion on what happens to a piece of lead in flight.

[swheeler]

LOL Newtire you and LoveLife must really like the Idea of that gain twist.
I don't have any experiance with the process personally I have heard from both sides of the camps for and against. I know that several barrel makers (quality) do offer this service and product at a reasonable rate. The Carcano I'm iffy on that one as most have been probably had more damage from bad cleaning methods than shot out. I think I would lean towrd a new barrel if I wanted to play this route for testing. It would be interesting to utilize it during this same Topic for testing because IF that gain was finished at the same twist say a 1-14 then it "could" show differant results as to where that "hurdle" is.

I thought Colt used gain twist barrels on their C&B revolvers, could be wrong though. Bartlein offers transitional rifling(gain twist) and suggest it could be useful for cast bullet shooting, but at a much lesser "gain" on the twist than as used in the Carcano.

[swheeler]

Darn it thank you I could not remember if Bartlien or Brux offered it.
I would have to look up the old Colt pistols but I suspect you are correct But right off memeory I can not validate that. I do know a Lot of Smiths made gain twist in Black powder and was reportably accurate.

I copied this from Bartleins site:
For a .22 rimfire shooter or a cast lead bullet shooter, we can increase the twist very slowly. As an example, from 1-16.25 at the breech and end with 1-16 at the muzzle, on any length of barrel being made. The rifling machine will automatically calculate out the twist rate over any given length of the barrel.

[swheeler]

I think the info for Carcano came from here, but could've been another site? Twist started at 11 and went to 8 at muzzle, I can see this not being good for cast bullets in them, lots of gas leakage by muzzle exit.

[Larry Gibson]

...........so my final thought.........just because someone says this is the way, does not mean he is right...or wrong.....anything is possible with cast if you seek it....you may fall face down in the mud trying, but you will get farther swinging for the fence........ is all I got to say...good day/good week/good life/goodbye.

I am not a "mod" but I have been on this forum a long time. This how I see it; first of all I don't think this discussion or any one like it is "bringing this forum to it's knees". If we didn't have discussions like these we would make no progress at all. We might just sit around in purple and sing "I love you, you love me". No one has to read this thread. They do because they want to. If they don't like it they can stop reading anytime. Everyone has their own mouse and bliss is just a click away if they don't like it.

Yes some have left. I have almost left a couple times myself in anger. But the more I thought about all the good members here who I helped and who helped me learn more about cast bullets I chose to stay. On of those who convinced me to stay was you 357maximum. You and I have disagreed several times, mostly based on semantics though. This is a forum. It is a place for discussion. Discussions by their very nature many times are opposing viewpoints. Granted we do need to conduct ourselves in a reasonable manner even though we may disagree. To those who don't like the discussions don't read them. To those who want to leave, leave. There are many members here with a lot of knowledge left to pick up the football and run with it. I've seen no lack of posting information or asking questions since several "old timers" have left. Enough said on that.

Now to the crux of my post; you are absolutely correct in that there are many ways to accomplish the same thing. No doubt about that. But those different ways are with in the laws of physics and ballistics. That is the problem with some; they think they have the power, knowledge or ways of doing something that will violate those laws. No matter how some may wish they did the fact is they don't. So, there are different alloys to use, different powders to use, different bullet designs to use, different lubes to use, etc. Yes there are a lot of variables we can use to do the same thing. But we are not going to violate or change the laws of physics and ballistics. The foolishness comes from those who think they can and argue vehemently that they can.

I understand that it is probable there is a "limit" to just how fast we can push a naked cast bullet of ternary alloy with accuracy (2 moa or less with linear group dispersion as the range increases). I do not know what that "limit" is with ternary alloyed naked cast bullets yet as I have not found it. I have found now through continued experiments measuring accuracy, velocity and pressure that there are other "games afoot" that seriously affect the solid state of the bullet. I have found the RPM threshold for these ternary alloyed naked cast bullets with barrels of 10" twist, of 12" twist and of 14" twist. I am next going to find it with the 16" twist. Each time I am able to control the RPM a higher velocity with accuracy is attained. The pressure and plasticization of the bullet during acceleration to such HV is now a problem to overcome if possible. Where the probable limit is I do not know.

I will ask once again to those who chose to post on this thread that my experiments are to determine how high a velocity we can push a ternary alloyed naked cast bullet to and yet maintain accuracy. That is with any twist. Let us keep to the topic of this thread. Please stop attempting to obfuscate the results of these test (for personal or any reason) by the use of other alloys or by posting what is "thought" someone else did. If you have conducted tests with targets, chronographed and load/test data with the use of ternary alloyed naked cast bullets that differ in results or are the same as these tests I have conducted then by all means post them. Let us discuss them. Those of us interested in this are interested "in the facts, just the facts". Let us continue to learn.

If you (btroj or anyone else) wants to push the RPM Threshold, jump it, hurdle it or whatever with whatever cartridge in whatever rifle then let's start a new thread and get on with it.

Larry Gibson

[swheeler]

Didn't mean to muddy the waters, the gain twist subject was brought up so thought I would add some info, sorry. No Hijack Intended.

[ol skool]

Larry:

noobie here, THANK YOU for your hard work, meticulous records and clean experimention. I (maybe the only one) am VERY interested in seeing your data for the 16" twist esp. relative to 14" twist you have tested. I couldn't determine whether you had it in hand or was waiting for it, nonetheless I have a request. If you have that gun ready to go, back away from the computer and go shooting.

Take Care,
Steve

PS: dtknowles post #132 - Good catch, real time data...