Ideal twist rates for cast boolits vs. jacketed. Different? Why?

[butch2570]

There was so much go info on this thread , wow.. But ever wonder how many things that B, Larry ,Gear and some others agree on? Many ,many things on many different topics.. But still there is no way everyone could have the same exact trial and error outcome on the fore mentioned topic, too many variable at play, No One should go away from this thread sour, just difference of opinions and as long as there are different people there will always be different opinions , self trial will be the deciding sum of these problems for the individual and said person's rifle /boolit/load etc.. You guys are too good, too much experience, and too much value to us younger guys here, to fall out over opinions of what has worked for yourselves. I'm nobody here, but I suffer when you guys clam up and won't share info, because of differences in opinion . Take it with a grain of salt and move on , YOU know what has and has not worked for YOU, but please don't quit sharing that with US ..

[john hayslip]

Lee Shaver, a gunsmith who shoots on our international muzzleloading team, who should know something about cast bullets stated in the last issue of Single Shot Exchange, that the most accurate bullet will be marginally unstable. Not sure that clears up anything but it is something to think about.

[MBTcustom]

The sky is blue.
No it's not, it just appears that way to your eye.
Appearance is all that really matters to anyone.
Your wrong, you can't extrapolate any scientific conclusions from bad information.
Saying the sky is blue is not "bad information". It's taking all the information as a whole.
It can't be good information if you have to ignore science to draw a conclusion.
The sky is still blue.
No it's not.
Yes, actually it is.
That's your perception and nothing more.
My perception is all that matters to me.

LOL!

Look fellers, why is it neccisary to convince someone else to agree with you? If your personal conviction about how to shoot cast lead is on such shaky ground that you feel you need everyone to agree with you in order to make it so, then perhaps you should modify your thinking so that you have a more comfortable ground to stand on?
I don't agree with Larry on everything, but I'm perfectly happy to disagree without ramming my opinion down his or anyone elses throat.
I give Larry props because he explains his position very well, and offers targets, referances, and pictures to back him up. That doesn't make him right, it just gives his point of view credibility. If you're going to convince someone who has an open mind (like me) to run a few tests and see if things line up, then that's the civilized way to do it.
Simply listening to someones opinion doesn't create a need for me to change mine. It doesn't have any effect on me whatsoever except to encourage a little broader thought. That does no harm at all.

If you go to college, or higher education of any kind, (which I know most of you have) you learn real fast to hold your views tight, but listen to others. In fact, since the person whom you disagree with is running the class you need a good grade in, you have to understand their view and be able to give it back to them the way they require it. By the time you get your diploma, you're a mental chameleon but you are also very able to argue your position with civility to anyone.
Only a knuckle dragger says "dis is da way it is, and me and my goons is gonna smash anybody dat says different".

Look, this RPM thing is a subject of a lot of contention. Why are there such hot debates over this? I'll tell you why, because nobody has all the answers yet. No one can say "look here, it's obvious!".It's not.
Larry Gibson has some of the best tools a fully fledged gun nut can possibly own, but he still has never seen what really happens to that boolit because he's never been able to watch it all the way from the case mouth to the target.
Now, each person is fully committed to their point of view, and I applaud that, but that's not what seems to be the issue here. Certain people wish they had a following of people that understand their view, or are jealous of certain others that have done all the handshaking, guiding, reinforcing, writing, and schmoozing required to build a following. All I can say is get off your butt's and start explaining yourself to lots of people and you'll get a bunch of folks that understand what you are saying and will back you up! Not only that, but I would think it would save a tremendous ammount of powder and primers on your part if you have 100 shooters reporting their findings and backing your position with every post.

Regardless, you have to understand that cast boolits is not a place to fight about your differences online. This is a place to humbly submit your position, and post your experiments. This is a place to grab the next rung on the ladder and give a helping hand to the guy two rungs down, and sometimes give a push to the guy that's two rungs up.
If any of you think that you are at the top, looking down on the rest of us trying to climb, you need to either turn around, or get off the ladder. Something else I might mention is that the castboolits ladder doesn't go to the clouds. It has a limit. You can only learn so much here, and then castboolits will fail to feed you anymore.

I would encourage everyone who is trying to learn this sport here, that if you learn nothing else here, you must learn to feed yourself, because someday, that's the only way you will advance. It's bitter when you reach the limit of what we can teach you, and you find there are no more teachers. When you realize that there are only one or two guys that are ahead of you. Sure they can give you a hand (maybe) but their viewpoint is going to be very narrow. It's one mans experience, and as such, is fallible.
I'm glad that I'm not anywhere near the top rung, because at this time I have many many teachers, but I know that will come to an end someday, so I am trying to learn how to learn for myself. After all, that's how Larry, Bob, JD, Molly, and so many others managed to get where they were. To say nothing of shooters like Fryxel, Ackley, Keith, McGivern, and others got to where they were. They were good at teaching themselves, and they were good at writing down their opinion. That's it. They put their pants on one leg at a time just like the rest of us, but they used their brains for more than to keep their ears from slapping together, and they wrote about what they did.
This is just a forum. This is lightweight training for the major leagues.

[Love Life]

The only way to glean the info is to shoot. I don't know why people are busy pushing their opinions down each other's throats. Do the tests and...PROVE IT OUT!!!

I had a theory on slow powders and barrel life. I dropped near $400 on a barrel and proved my theory was wrong by burning the barrel out.

You all have accurate rifles coming. Put the ammo together, shoot it, take notes, compare notes, report back.

It's ok to be wrong, it's ok to be right. You all have the tool (gun) coming to aid in your reseach. Now you need near perfect boolits...

[MBTcustom]

The only way to glean the info is to shoot. I don't know why people are busy pushing their opinions down each other's throats. Do the tests and...PROVE IT OUT!!!

I had a theory on slow powders and barrel life. I dropped near $400 on a barrel and proved my theory was wrong by burning the barrel out.

You know, I never really gave you props for that Love Life. That was inspirational to say the least, and that rifle taught me more than any other up to this point, so thank you for letting me build it for you! That's the way to run an experiment by gums! Put your money where your mouth is, roll the dice, and write down what happened good or bad.
Awesome.

[Love Life]

I had to know, and all I proved was each rifle is a law unto itself.

It started with me wanting to know WHY a 308 barrel is good for 5,000+ rds (maybe a little less if you fire hot and fast non stop). The answer there seemed to be pressure and the fact it is a balanced cartridge.

Then that was turned upside down by George Gardner from Gnats A** Precision (GAP) rifles when he brought out the 6.5 SAUM. It is a 6.5 caliber launched at 3100 FPS using H1000 powder. Using his load it stays in the same sedate pressure envelope of the 308 Win, but has some juice behind it. He went on to win the Sniper's Hide Cup with over 4,000 rds on that barrel.

So, an overbored cartridge with slow powders and he went to 4,000 rds. Others shooting the cartridge report much the same. The kicker is that Mr. Gardner and others didn't baby the barrel by taking an hour to shoot 5 shots. They shot how they pleased.

I got to thinking and figuring. Doing the math, using Retumbo in the .243 with the 105+ gr weight class of bullets would keep me in 308 pressures. So if 1+1=2 then I should have gotten way more than 820 rds out of that barrel before it croaked. As we all know, that was NOT the case at all...

Of course this has no bearing on twists and such, but it just goes to show that the amount of variables facing this equation is staggering.

Then you throw cast boolits into the loop which adds another entire layer of variables. Does the boolit have voids? Where? Was it well filled out? Good lube? Who knows? As we know, boolits are finicky little monsters. I'm wondering if this quest should be conducted with swage paper patched boolits, as the little variables in necked and lubed boolits may cause issues that give false positives and negatives.

[Love Life]

To address the thread question: Ideal twist rates for cast boolits vs. jacketed. Different? Why?

I believe the lowest rung ( think 55 gr FMJ fodder) swaged jacketed bullet is still head and shoulders above the best cast bullet. Lack of voids, plus you have that tough jacket to take the stank from the barrel. Just my opinion on it.

With jacketed you have wiggle room. With cast it is an all or nothing proposition.

[ol skool]

[I]...You can strive for cast bullet perfection and launch or you can slow the twist down to keep the RPM under 140,000.

Yes that requires a different barrel. But if building a cast bullet shooter why not consider the slowest twist that will properly stabilize the chosen cast bullet? Note here there is a difference between minimal stabilization and "stabilized" as far as twist rate goes. The idea that a slower twist some how limits you to just the one cast bullet and some how is not "versatile" is mistaken...Larry Gibson

Ok. Total noob here. I see ego's getting in the way of good info that I need to use for my paralysis by analysis. So I'm going to interject a stupid question. You know, kind of like when your 4 year old kid comes up and asks if you and Uncle Remus (brother) are not going to be friends anymore. (Anyone else a Zappa fan?)

So I'm pondering reboring a 308 to 338 for this boolit primarily but may want to use a 225gr Lee at some point in the future. Hence my interest in this thread.

What is the minimum RPM to stabilize a boolit so I can calculate a twist for the barrel that may work for the heavier Lee as well? I'm calculating max RPM by (mvfps x 60 seconds) * (12 / twist). Is there another magic formula?

Also smearing, deformation... How many gooves, eh? There's a new question, huh? I can't see it would matter as long as it's not micro-groove. But thought I'd ask...

[MBTcustom]

Ok. Total noob here. I see ego's getting in the way of good info that I need to use for my paralysis by analysis. So I'm going to interject a stupid question. You know, kind of like when your 4 year old kid comes up and asks if you and Uncle Remus (brother) are not going to be friends anymore. (Anyone else a Zappa fan?)

So I'm pondering reboring a 308 to 338 for this boolit primarily but may want to use a 225gr Lee at some point in the future. Hence my interest in this thread.

What is the minimum RPM to stabilize a boolit so I can calculate a twist for the barrel that may work for the heavier Lee as well? I'm calculating max RPM by (mvfps x 60 seconds) / (twist / 12). Is there another magic formula?

Also smearing, deformation... How many gooves, eh? There's a new question, huh? I can't see it would matter as long as it's not micro-groove. But thought I'd ask...

Assuming you are talking about 338 federal (I gotta get me one a them!) and you're wanting to shoot right around 2400fps, I would think a 20 twist would be the minimum you would want to go.
You could feasibly go as far as 21, but my chest aint hairy enough to recommend that. At 21 twist, if for any reason you can't get above 1800fps, you are going to be on really shaky ground.
That said, I like to hedge my bets, and if I were to do what you are contemplating, I know I would get 18 twist.
Just like with the 30 cal. btroj said 12, Larry Gibson said 16, I'm standing right in the middle at 14 and calling them both nuts! LOL!

Oh, and I would go three groove. I have no reason except I like odd numbers and it works.

[Larry Gibson]

ol skoo

A 16" twist will fully stabilize that bullet from 1500 fps up. With the 338-.308 or the 338-06 the maximum velocity obtainable will be under the RPM threshold. Thus accuracy from the 1500 fps upwards of the maximum for either cartridge should be very good with a properly designed cast bullet if you do your part. The potential limitation I see with that bullet is it is designed for hunting at somewhat lower velocities. The limiting design features appear to be; the bearing surface is at or less than 50% and the a major portion of that long nose is unsupported. Those 2 design features may lower the RPM threshold in either cartridge and accuracy may not be the best above 2100 - 2300 fps unless a very hard alloy is used. An 18 or even the 20" twist goodsteel recommends may attenuate that problem but the minimal velocity for stabilization goes up. Thus with those slower twists that bullet may be only useful at top end velocity. Whether the design features of that particular cast bullet will allow that would have to be seen. That is why I fudge to the side of the 16" twist.

Larry Gibson

[MT Gianni]

I don't think that is the cause. So far I've read it, as have others, since the first page and has been a topic of conversation off this site. Geargnasher has the just of it below...........................

Bob, overall it has had less that 1500 views. Many in Our Cast Boolits have 5-6 times the views in a similar time period.

[HollowPoint]

I started following this thread with some interest but I quit reading when folks started butting heads. It's hard to get usable new information under these circumstances.

I came back to reading this thread because I've always wondered about some of the same questions that were asked by the OP. In my minds eye I picture a potential culprit to at least a couple of the questions posed by this thread as having to do with imperfectly cast boolits that appear -superficially- perfect.

You know, those invisible voids that have already been mentioned before. It occurred to me to ask if anyone has made a lead bullet swaging die for a given 30 caliber lead bullet so that it could be formed via a swaging die rather than cast using a bullet mold? This may be a good way of eliminating the possibility of unseen voids or imperfections in our cast bullets; at least for testing purposes.

By eliminating the invisible imperfections we eliminate one of the potential factors that cause us grief regardless of velocity or twist rate. My cast bullets shoot well enough at velocities up to 1700 fps but I'll inevitably get one or two or three or four that have a mind of their own and go off as "Fliers."

I have two 30 caliber rifles. One is a 10-twist and the other is a 10.6 twist. I've shot both of them at just a tad over 2000 fps before and neither one would group worth a darn at a hundred yards. Neither did either one leave leading in the bore or oblong holes in my target.

Was this due to imperfections in my cast bullets that I didn't know about or was it due to an "RPM/Barrel Twist" thing that was eluded to by the OP? If your bullets ARE cast concentrically, loaded concentrically and flying concentrically, it's hard for me to wrap my head around "RPM" or "Barrel Twist" as being the problem.

It's right about now that a good lecture on BHN and Paper patching would come into play.

HollowPoint

[Love Life]

I too have been kicking around the idea of a set of swage dies to swage some lead rifle bullets (I think they are bullets because they are swaged). However; the issues in my mind with that are:
A) A suitable alloy. Will the swage dies be able to swage the harder alloys?
B) Lube. I reckon you could cast first of your preferred alloy in a lub grooved boolit mould, lube the groove, and then swage it to final shape. That would eliminate voids and leave some lube...I think. Would it leave enough lube though?

[geargnasher]

Swaging can help, LL, but it will by no means mitigate the need to understand how to dance the Rhumba with the big, purple elephant. You're still thinking from a jacketed bullet frame of mind, which won't get you very far with cast.

Gear

[Larry Gibson]

Swaging can help, LL, but it will by no means mitigate the need to understand how to dance the Rhumba with the big, purple elephant. You're still thinking from a jacketed bullet frame of mind, which won't get you very far with cast.

Gear

Very well put, concur 100%.

Larry Gibson

[35 shooter]

goodsteal i can't offer anything constructive on your bbl twist theories, although you have got my head spinning on it lol. I would however like to get your and Larry Gibson's opinion on the 358009 280 gr. boolit in 35 whelen in a 14 twist bbl. I may get 2 different opinions and that will be just fine, i'll figure it out through testing from there. How fast can that boolit be pushed while maintaining 1 to 1 1/2" accuracy (i know that will be just best guess) using something along the lines of h4895 to imr4350.
I already get that and better with a 200 gr. boolit at 2400 to 2500 fps, i just want to play with a heavy weight for caliber and don't want to make the wrong choice.
goodsteal i hope this thread comes back strong because you certainly had my attention on it. Didn't intend to post...just learn something new maybe, but since it drifted a bit just thought i'd ask your opinions on the above.

BTW i think most folks here WOULD love to shoot with Larry...not to prove anything,but just a chance to absorb some of that encyclopedia of cast boolit knowledge he's carrying around in his head. He sure better be glad i don't live next door lol!
Stop the jabs and let the learning curve continue.
Okay, sorry if this was a drift...looks like everything got going again while i was posting.

[Love Life]

Swaging can help, LL, but it will by no means mitigate the need to understand how to dance the Rhumba with the big, purple elephant. You're still thinking from a jacketed bullet frame of mind, which won't get you very far with cast.

Gear

Maybe, maybe not.

Perfect or near perfect boolits has been mentioned and discussed as being important to many things.

I pay good money for near perfect jacketed bullets and they do what they are told. Yes the jacket is a whole different variable...

So, swaging will give you a much better product to launch down your bore. Have any of you done it with swaged bullets (lead/alloy)? What I'm seeing is that the elimination of one of the most nagging variables very well may open the doors or part the clouds.

So yes, in that sense I am in the jacketed frame of mind. We have the ability to actually make perfect bullets (by opening the wallet of course) but everybody sticks to their preciously poured boolits into inert mould blocks, and they have no way in ensuring any consistency. Real consistency. Not just "My driving bands are well filled!!", but real, quantifiable consistency.

It's like trying to do brain surgery with a Ka-Bar.

However; I will not get hung up on that here. I will continue to listen to the mantra of "Fit, Fit, FIT!!! Boolit, Neck, Chamber, etc.!!"

I get it and I got it. I'm not retarded. I'm listening.

[Love Life]

Very well put, concur 100%.

Larry Gibson

Amazing!! Good thing I get to ignore neck tension, diameter, etc and just sit some bullets over 'splody powder and shoot sub-moa to 1,000 yards.

I apologize for the snarkyness, but brass prep and all that jazz is just as important in shooting jacketed. What I don't have to deal with in jacketed is sub par, off balance, projectiles...that may or may not act like accordions.

[Larry Gibson]

It does, sorta.

Treating a cast bullet the same way you treat a jacketed bullet at ignition is a sure way to fail. The cast bullet is fragile in comparison and needs to be treated accordingly.

Start it soft and gentle and straight and don't do anything that may let it get deformed. Throat fit is soooo critical.

Very well put, concur 100%.

cbrick

I think that was basically (very "basically" because there have been long posts, a lot of posts and some very long threads on how to do that) what geargnasher was saying. My understanding of what he was saying anyway.

Larry Gibson

[geargnasher]

Maybe, maybe not.

Perfect or near perfect boolits has been mentioned and discussed as being important to many things. It has been discussed, but most of those discussing it really don't know enough about it, but are speculating theoretically. Theoretically, we can't cast a perfect enough boolit to shoot well at HV. But I assure you many of us can and do, even those who can't shoot HV with accuracy in fast-twist barrels are casting boolits that are plenty good for the job, they just don't know how to dance with the elepant. Lots of us know how well an as-cast boolit can shoot at extremely high velocity and RPM. I do. Pdawg Shooter does. Nobade does. Bob does.

I pay good money for near perfect jacketed bullets and they do what they are told. Yes the jacket is a whole different variable...Think about how a jacket helps us dance with the elephant, and apply that to your cast boolits.

So, swaging will give you a much better product to launch down your bore.No doubt, but I can tell you that you can cast a more than adequate projectile the old-fashioned way, it isn't that difficult, and it doesn't matter as much as you think. Have any of you done it with swaged bullets (lead/alloy)? What I'm seeing is that the elimination of one of the most nagging variables very well may open the doors or part the clouds. The theory of hidden voids/weak spots/balance problems has been disprove in a different way. All your swaged boolits will prove is how good you are at dancing with the elephant, or not.

So yes, in that sense I am in the jacketed frame of mind. We have the ability to actually make perfect bullets (by opening the wallet of course) but everybody sticks to their preciously poured boolits into inert mould blocks, and they have no way in ensuring any consistency. Real consistency. Not just "My driving bands are well filled!!", but real, quantifiable consistency.A micrometer and loading scale are more than sufficient to cull boolits that aren't adequate for HV application.

It's like trying to do brain surgery with a Ka-Bar. I think a better analogy is trying to perform brain surgery with only an RN's tools and level of training.

However; I will not get hung up on that here. I will continue to listen to the mantra of "Fit, Fit, FIT!!! Boolit, Neck, Chamber, etc.!!"

I get it and I got it. I'm not retarded. I'm listening.

Achieving proper static and dynamic fit, together with load balance (pressure curve, harmonics, etc), will get you a lot further than swaging perfect boolits and using cave-man loading techniques.

Now, Rick, don't worry, I'll get to it, and hopefully so will those who know more about it than I do, but for right now, some thinkin' needs to be done here.

Gear