at present im building up a 375 ruger and 416 ruger, with the 375 i have gone with a 1 in 10 twist and the 416 ruger i have gone with a 1 in 12 instead of a 1 in 14 ...what effect will this have on useing cast bullets as far as accuracey goes
Daniel

quote:

Originally posted by M 98:
at present im building up a 375 ruger and 416 ruger, with the 375 i have gone with a 1 in 10 twist and the 416 ruger i have gone with a 1 in 12 instead of a 1 in 14 ...what effect will this have on useing cast bullets as far as accuracey goes
Daniel

Larry Gibson will tell you that there is a RPM threshold and the faster twists get there quicker and accuracy goes bad, but I don't say that. Doesn't matter in your case because you're shoulder will give out before you reach that threshold. Just get out there and try it to see how it does and I think you'll be pleased.

STARMETAL;
what do you mean by the "shoulder will give out"...can you explain that
Daniel

quote:

Originally posted by M 98:
STARMETAL;
what do you mean by the "shoulder will give out"...can you explain that
Daniel

I meant by the time you got the rpm up to where Larry claims the accuracy would go bad that your velocity would be pretty high and same with the recoil...LOTS OF RECOIL!!!!!

M98

There is indeed an RPM threshold and you will find out with that .375 with 10" twist. You will begin to lose accuracy at 1900-2000 fps. That is not, with 250-300 gr cast bullets, a lot of severe recoil as Joe insinuates. The reason is RPM will be much quicker with the 10" twist at those velocities than if you had a 12 or 14" twist. My M70 .375 H&H has a 12" twist and I maintain excellent accuracy up thorugh 2200+ fps with 275 gr cast bullets. With the .416 you will probably be within the RPM threshold and maintain good accuracy up through 2200 fps velocity with 400 gr cast bullets. Lighter cast bullets driven faster than that in the .416 are then subject to the RPM threshold and the recoil as Joe mentions.

This is with GC bullets of common design (readily availble) cast fairly hard. Also lets discuss what "accuracy" is here. If you can shoot 1-2" groups with cast in that .375 at 1800 fps then the accuracy lost up through 2200 fps will probably be to 3-5" groups. That may be acceptable to you, it is to some and not to others, just depends on what you want.

With the .416 you can approach factory ballistics with 400 gr cast with acceptable "practice" accuracy up through 2200 fps. You will not be able to do that with the .375 using cast bullets in the 250-300 gr range and driving them to 2700+ fps. Accuracy will get pretty bad above 2300 fps or so in your .375.

Some will adamantly disagree with me but I'll simply advise you to try it. If what I'm telling you isn't so then please return here and correct me by showing us the groups you shot (100 yards please - 50 yards doesn't show much) and the actual velocities recorded. I'm a big boy and can admit to being wrong.

Larry Gibson

quote:

Originally posted by Larry Gibson:
Some will adamantly disagree with me but I'll simply advise you to try it. If what I'm telling you isn't so then please return here and correct me by showing us the groups you shot (100 yards please - 50 yards doesn't show much) and the actual velocities recorded. I'm a big boy and can admit to being wrong.
Larry Gibson

A couple of folks showed you high velocity sub MOA groups and you didn't say much of anything. Your gonna have to explain yourself on that.

Larry did say some magic words which were "try it". I suggest this too and you will be pleasantly surprised as long as you do your cast bullet loading homework. That is correctly sizing the bullet (which can mean not only proper size according to the groove diameter, but also fitting the throat), proper alloy, and a good lube. Keep us informed as you progress along.

Joe

quote:

Originally posted by 45 2.1:

quote:

Originally posted by Larry Gibson:
Some will adamantly disagree with me but I'll simply advise you to try it. If what I'm telling you isn't so then please return here and correct me by showing us the groups you shot (100 yards please - 50 yards doesn't show much) and the actual velocities recorded. I'm a big boy and can admit to being wrong.
Larry Gibson

A couple of folks showed you high velocity sub MOA groups and you didn't say much of anything. Your gonna have to explain yourself on that.

45 2.1

I do believe I adaquately explained it on the other forum but for your benifit I will again here, in short form anyway.

High velocity does not necessarily equate to high RPM. It all depends on the twist of the barrel and the velocity. Several of the mentioned groups had not exceeded the RPM threshold and those that did merely pushed the RPM threshold, as I always said could be done. Obviously you still haven't paid attention to what I've said before and I doubt you will now. The point is; The RPM threshold is just that, a threshold. It is not a "limit" as you continue to think. Accuracy at high velocity and high RPM can be had but it is a difficult thing to attain and is many times fleeting. Had you paid attention to my writings on the subject you'd have known I've attained very good accuracy at high RPM with Bass's LBT bullet and 311466. I, like many others, also get accuracy at high velocity with cast bullets in some rifle/cartridge combinations because the twist rate is 14"+. As we've discussed before you claim "high velocity" with the 6.5x55 Swede with its very fast twist. Yet the actual velocity you get is in the 1800 fps range (careful in your response, I have your PM to me with you stating such). That my friend is not really "high velocity" with regards to the 6.5x55 Swede when 140-160 gr jacketed bullets do 2400-2700 fps. Your 6.5 Swede loads only just push the RPM threshold. I've told you before that is what you are doing. You failed to understand that then and I suppose you will now.

So there's the explanation which I seriously doubt you'll pay any attention to as you've not paid any attention to anything else I've said on this subject. You've especially not paid any attention to anything that disagrees with your own opinions. That's fine with me but apparently it's not to you.

As Joe points out, I asked M98 to go ahead and try it. I even challenged him to succeed and hope he will. However I doubt he will get equal accuracy at 2500-2700 fps with cast bullets of equal weight to jacketed bullets in that .375 with a 10" twist. He will stand a better chance with the .416 with a 12" twist up through 2200 fps with cast bullets. But I think Joe might have been correct regarding recoil on that one. 400 gr bullets at 2200 fps are not to conducive to accurate shooting off a bench. A few rounds yes but the shoulder will give out as Joe mentions.

Larry Gibson

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by 45 2.1:

quote:

Originally posted by Larry Gibson:
Some will adamantly disagree with me but I'll simply advise you to try it. If what I'm telling you isn't so then please return here and correct me by showing us the groups you shot (100 yards please - 50 yards doesn't show much) and the actual velocities recorded. I'm a big boy and can admit to being wrong.
Larry Gibson

A couple of folks showed you high velocity sub MOA groups and you didn't say much of anything. Your gonna have to explain yourself on that.

So there's the explanation which I seriously doubt you'll pay any attention to as you've not paid any attention to anything else I've said on this subject. You've especially not paid any attention to anything that disagrees with your own opinions. That's fine with me but apparently it's not to you.

Larry Gibson

Larry-
It simply amazes me how you can go off on a tangent and obfuscate things. The high velocity sub MOA group was from 357 Maximum. His group was something on the order of 0.6" at 100 yards at over 2600 fps out of a 35 Whelen. that is on the order of over 156,000 RPMs. You were quite silent as to an explain/denial of that group or for that matter the groups posted by BABore, neither of which you could come close to matching at your vaunted much lower velocity. And here you go posting a long winded diatribe about something else. As for my 6.5 Swede groups, you couldn't match what I posted let alone the higher velocity stuff that you know nothing about.

Too bad some folks take this forum as their personal pissing match, but so be it.

To the original post, I think you'll find that the riflest that have issues with twist causing accuracy problems are those with truely fast twists, i.e 1-7, 1-8. There are many folks that have gotten fine accuracy in 1-10 twist 30-06 pushing 2200-2400 fps.

I will say getting top accuracy in rifles with velocities over 2000 fps can take more work than at lower speeds. But that doesn't mean it can't be done. A good bullet design sized to your chambers throat, using a good lube and gas check should produce good results.

If I were going for a purpose built cast rifle I'd likely go with slower barrel twist 1-15 to 1-18, depending on what bullet weights I planned to shoot. I'll freely admit to being lazy and try to stack the odds in my favor. Slower twists in general are more friendly to cast, so you might as well make life as easy as possible on you.

Paul H

Thank you for that fine post. Perhaps 45 2.1 will realise from your post that it can be done, i.e. the RPM threshold can be pushed. It just takes some to get there as I said and now you have said. It is unfortunate that he just can not grasp that fact. He keeps posting examples trying to prove me wrong but only, in the end, proves me and now you correct. The RPM threshold is generally 125-140,000 RPM. I guess he doesn't understand that 156,000 RPM is "pushing it". He also neglects to add that I did have a discussion with .357maximum regarding his loads in his .35 Whelen. Thanks again Paul for your comments. I'm through with this thread as 45 2.1 will continue to come back at me as always. My apologies for that.

Larry Gibson

Don't get too over blown Larry. Paul also said that MANY shooters could get good accuracy with the fast twists in the 30 calibers. He did say it was harder in the extreme fast twist (which we can take as the 6.5 Swede for example) with more work. Definitely not a task for the amateur
cast bullet shooter. I can equate his "if he were building a dedicated cast rifle" he'd go with a much much slower twist to a person would select a quarter mile race car or Indianapolis 500 car for daily work commute in town....although they'd get you to work. I don't think I'd want a faster twist than needed in a rifle for shooting only jacketed bullets and not because of any accuracy issues, but for all the other things that fast twist does in high velocity jacketed shooting. You know what I'm talking about there.

Joe

Not "blown over" at all. "Fine accuracy" can be had at 2200-2300 fps in 10" twists but it still takes some work to get there. As Paul says it takes a good fit to the throat, a good lube and quality GCs. I'll also state additionally it takes the right bullet. Most bore riders do not fit correctly and won't make the grade. Some bore riders have noses that fit correctly and when one is found the shooter can approach 2200 fps with decent accuracy. However, above 2200 fps most all bore riders will begin to lose accuracy given a 10" twist barrel. There are exceptions as always but they are truely rare. With a well designed bullet like LBTs or Loverns good accuracy is quite possible up through 2400 fps out of a 10" twist barrel. All the things just mentioned and then some additional ones are the ways to "push" the RPM threshold. I proved that pretty conclusively in my recent tests.

You will find the same results at the same RPM with the 6.5 Swede and in other faster twists. However the velocity at which good accuracy is achieveable will be much lower.

Another consideration we should answer is what is "good" accuracy, what is "fine" accuracy and what is "consistent" accuracy? Are we talking 3 shot groups, 5 shot groups or 10 shot groups? Are we talking 50 yards, 100 yards or farther? Are we talking picking the best few shots out of a string, ignoring the flyers and calling them good groups?

My own preference is to initially test at 100 yards. I shoot 5 shot groups for load development. I do not ignore flyers. I then shoot 10 shot groups for consistancy. When I find a consistant load (one that groups consistently for the 10 shots and has a proportionally good SD/ES) I then test at 200 yards or if it is a HP match load I then test a 22 shot string. That's what I do. Using rifles of moa or better accuracy with quality jacketed bullets I call consistent 10 shot groups of less than 2 moa as "fine" accuracy. I call call consistent 10 shot groups of 2-3 moa as "good" accuracy. Excellent accuracy to me is two fold; first is a 10 shot moa group at 100 yards that is repeatable and second is a 22 shot group of 2 moa at 200 yards that is repeatable. A "consistent" group is one where the string has a proportional SD/ES of velocity (usually with the ES of a 10 shot string being 50 fps or less). The other criteria of "consistent" is that the accuracy must be repeatable on demand.

That's where I stand on this Joe. I have shot some 4-5 moa 10 shot groups at 100 yards at 2500-2600 fps out of a 10" twist. That might be "fine" or "good" to some but it is not to me. Like you I have shot cast bullets at 2800-3000 fps and "held paper" at 100 yards. However, "holding paper" is not my idea of acceptable accuracy. Conversely I have shot quite a few sub moa 5 shot groups at 100 yards. They were not the average of what that rifle/load would do...they were the best it would do and they were never repeatable on demand. I know lots of guys who carry around tiny groups in their billfolds and will pull them out quicker than granny with the grandkids photos! Trouble is it was only the one group and when asked to repeat it they couldn't. Always some reason why but they still couldn't repeat the group. I am interested in consistent accuracy of a load day to day out of any firearm, not just one really nice group. What kind of accuracy are you interested in?

Larry Gibson

Time for change Larry, you're getting to sound like the politicians currently running, same old same old.

quote:

Originally posted by Paul H:

To the original post, I think you'll find that the riflest that have issues with twist causing accuracy problems are those with truely fast twists, i.e 1-7, 1-8. There are many folks that have gotten fine accuracy in 1-10 twist 30-06 pushing 2200-2400 fps.

I will say getting top accuracy in rifles with velocities over 2000 fps can take more work than at lower speeds. But that doesn't mean it can't be done. A good bullet design sized to your chambers throat, using a good lube and gas check should produce good results.

.

Paul- I think you are absolutely correct in this post. I know I have shot sub 0.5 MOA 10-shot groups in registered competition with 196 to 215 grain cast bullets of .3115" diameter, and 5-shot groups in the very low .2s (as low as .211") with the same bullets. All were going at 2150 to 2300+ fps through 1-in 11" twist Hart, & Harris, barrels.

I actually think that is easier than doing the same thing at say 1,800 fps. It is for me, anyway. The bullets seem to be less affected by wind, probably because the wind has less time to act on them. The powder may also be burning more consistently at the higher pressures required to reach those velocities.

quote:

Originally posted by Paul H:
Too bad some folks take this forum as their personal pissing match, but so be it.

I assume you meant this for me Paul. I don't have any problem with Larry accept for his "theory". Many people, such as Alberta Canuck above, have gotten excellent results at high velocity, ie above Larry's limit of velocity. Larry would relegate everyone to 1600 fps to get "good" accuracy. If Larry's "theory" was true, then jacketed bullets would be held to the same criteria, but they're not, are they. The main factor is the skin/core strength of the cast boolit, not whether it is spinning at a certian rate.
These forums are about teaching people to get better results I believe, not tell them you can't do any better than I did. In Larry's case, people are doing much better than what he says will happen. If that is pushing it, then perhaps those folks need to learn some more.

Alberta Canuck

That is very good and an excellent example of what I'm talking about. Those loads are at the top end of the RPM threshold or are just pushing it (140-150,000 RPM). Having a very nice custom barreled (top end barrel at that!) rifle certainly helps. You are probably correct about the powder (assuming a medium or slow burning powder) "burning more consitently" at the higher velocity. That has been my experience measuring tousands of loads with chronographs and measuring the pressure curves with the M43.

A couple questions if you don't mind;

What kind of rifle/action? What bullets? Assuming benchrest competition?

Thanks for the input.

Larry Gibson.

Joe

Facts are facts. Restating them is not political, it is factual. You want agreement then come up with something agreeable

Do we assume by your absence of an answer to my questions that "holding paper (I believe you said it was 24x24") at 100 yards" is your accuracy standard for high velocity cast bullets? I'm not being fececous here Joe. If you and 45 2.1 are going to criticise the RPM threshold theory and me then kindly answer what your accuracy standards are for high velocity cast bullets and what "high velocity" is. That would then give us a realistic base to discuss this issue from. As it is my standards appear to be a bit different from yours.

Larry Gibson

My comments were directing to everyone, it takes 2 or more for a pissing match.

As to fast twist, slow twist, accuracy et al... We make comments based on our experiences, and often times our views get skewed based on a few good or bad experiences. I can see my post got slow and fast twisted

In generaly I don't have much free time, so I seek maximum performance from minimal effort. I was in on the old feller 6.5mm bullet mold deal way back when. Based on comments from others, and my experience, I found that trying to get cast accuracy from a fast twist 6.5mm swede was a challenge. It could be that paticular gun just wouldn't shoot cast, but I didn't put the effort in to see what it would take to get accurate cast loads. It simply wasn't worth the effort to me.

I've shot a fair bit of cast through a .308 with a 1-12 twist, and a 35 whelen now 350 rigby with a 1-14 twist, and thousands of rounds through various 357 mag and 357 max pistols. I've even driven 200 gr cast 1900 fps from a 10" 357 max, and 2000 fps from a 14" 357 Herret. That has lead me to believe the slower twists are more friendly to cast. I've gotten decent to excellent accuracy with minimal effort. I cast, visually inspect then lube/size my bullets, and if a gc the gc gets set in the lube/sizer. I've never weighed a single cast bullet. And with that minimal work I can get 1-2moa accuracy. If I get a handgun or rifle to put 5 shots into a 1" group at 50 yds, I'm content.

I know some folks are passionate about cast bullets, and put hours upon hours casting, sorting, inspecting, working up loads and shooting. Some of those folks will put cast bullets through every conceivable weapon, others concentrate on black powder, some bench rest, some handguns, etc.

Most seem to have missed the original posters question. He wants to shoot cast through several sporting rifles and was looking for some general comments on the affect of barrel twist on accuracy. My thoughts are in a genearal sense, the bigger bores are friendlier to shooting cast. If he keeps his velocity to 2000 fps, he should have little trouble getting acceptable accruracy. If he wants to push those bullets to 2200-2400 fps, then he'll likely find that he has to put more work into testing bullet alloys, hardness, sizing and working up loads. If he was building the guns as purpose built cast shooters, I'd recomend a 1-14 twist, as it should make it easier to get top accuracy from cast bullets.

quote:

Originally posted by Larry Gibson:
Joe

Facts are facts. Restating them is not political, it is factual. You want agreement then come up with something agreeable

Do we assume by your absence of an answer to my questions that "holding paper (I believe you said it was 24x24") at 100 yards" is your accuracy standard for high velocity cast bullets? I'm not being fececous here Joe. If you and 45 2.1 are going to criticise the RPM threshold theory and me then kindly answer what your accuracy standards are for high velocity cast bullets and what "high velocity" is. That would then give us a realistic base to discuss this issue from. As it is my standards appear to be a bit different from yours.

Larry Gibson

Larry I never said that. I wish you'd get off that.

Folks I'm going to tell you what I told Larry. Over on the cast boolit forum there are many that think that long cast bullets (like the 6.5 Swede for an example) bend from the high rpm if you drive them fast. I disagree. So, not having a 6.5 Swede, I got some 70 gr 22 caliber cast bullets from the forum. Later I found out they weren't hard by any means and if I remember correctly they were just air cooled wheel weights. I shot them out of my Colt HBAR AR15 which has a 1-7 twist and well over 3000 fps. Now here's the part Larry keeps getting wrong. I put a piece of typing paper on my target backboard and a small black bull in the center of it FOR AN AIMING REFERENCE ONLY!!!!!! I will admit I was slightly convinced they slugs were going to go haywire such as many of the cast boolit forum boys said they would. I was in NO WAY conducting an accuracy test. Anyways the final results were they all stayed on that typing sheet, none flew off into Waksupi Wonderland (he's a member that believes they bend after release from barrel, proven by finding bent 6.5 bullets in a snow bank after a thaw...same as water boys, snow isn't exactly soft when velocity is introduced against it)none keyholed, and none exploded. That's what I told Larry Gibson and his think head keeps saying that's the accuracy I expect at high velocity for cast bullets. No, it's not, I'd expect those bullets, properly prepared, alloyed, loaded, to at least shoot 1-2 inches at 100 out of that particular HBAR. Larry hasn't told you about my 7mm-08 shooting the Lee 135 gr at 2640 into 3/4 inch group at 100 yards, using a Sako Mannlicher "CARBINE" none the less, with a 9 twist and a "MINI 3X9 SCOPE"...hardly a target set up.

Joe

quote:

Originally posted by Paul H:
My comments were directing to everyone, it takes 2 or more for a pissing match.

As to fast twist, slow twist, accuracy et al... We make comments based on our experiences, and often times our views get skewed based on a few good or bad experiences. I can see my post got slow and fast twisted

In generaly I don't have much free time, so I seek maximum performance from minimal effort. I was in on the old feller 6.5mm bullet mold deal way back when. Based on comments from others, and my experience, I found that trying to get cast accuracy from a fast twist 6.5mm swede was a challenge. It could be that paticular gun just wouldn't shoot cast, but I didn't put the effort in to see what it would take to get accurate cast loads. It simply wasn't worth the effort to me.

I've shot a fair bit of cast through a .308 with a 1-12 twist, and a 35 whelen now 350 rigby with a 1-14 twist, and thousands of rounds through various 357 mag and 357 max pistols. I've even driven 200 gr cast 1900 fps from a 10" 357 max, and 2000 fps from a 14" 357 Herret. That has lead me to believe the slower twists are more friendly to cast. I've gotten decent to excellent accuracy with minimal effort. I cast, visually inspect then lube/size my bullets, and if a gc the gc gets set in the lube/sizer. I've never weighed a single cast bullet. And with that minimal work I can get 1-2moa accuracy. If I get a handgun or rifle to put 5 shots into a 1" group at 50 yds, I'm content.

I know some folks are passionate about cast bullets, and put hours upon hours casting, sorting, inspecting, working up loads and shooting. Some of those folks will put cast bullets through every conceivable weapon, others concentrate on black powder, some bench rest, some handguns, etc.

Most seem to have missed the original posters question. He wants to shoot cast through several sporting rifles and was looking for some general comments on the affect of barrel twist on accuracy. My thoughts are in a genearal sense, the bigger bores are friendlier to shooting cast. If he keeps his velocity to 2000 fps, he should have little trouble getting acceptable accruracy. If he wants to push those bullets to 2200-2400 fps, then he'll likely find that he has to put more work into testing bullet alloys, hardness, sizing and working up loads. If he was building the guns as purpose built cast shooters, I'd recomend a 1-14 twist, as it should make it easier to get top accuracy from cast bullets.

....and my first post basically answered that similar to your posts. In fact Larry agreed with me that your shoulder would give out before you got to that upper upper velocity with something like a 375 . Yes, the faster the twist and higher the velocity, the more demand there is on the bullet...and caster/reloader/shooter.

Joe

Okay Joe, you win. That should make you happy. You to 45 2.1.


Paul

I agree 100% with you. I also believe that is what I told M98 in my first post here. I told him where he would find best accuracy with his 10" twist sporter 375 H&H. I told him what his accuracy will probably be at 2200 fps. I told him the accuracy I was getting with a 12" twist 375 H&H and explained why there would probably be a difference between his 10" twist and a 12" twist. I also told him to try it. Who knows he may indeed do everything right and get consistent 1-2 moa accuracy at 2200+ fps. I hope he does but I doubt he will. Thus I think we were on the same page in our advise to M98.

Let me give a brief example of how RPM above the RPM threshold adversely affects accuracy. On the Cast Boolet forum one of the biggest doubters of the RPM threshold theory stated basically that if accuracy increased in a linear fashion as range increased with a load above the so called RPM threshold then it would disprove the RPM threshold theory. He stated conversely that if groups with a load above the RPM threshold opened up non-linearly as range increased that would prove the RPM threshold. He also stated the test should be done using the same bullet in the same rifle with a load in or below the RPM threshold. At his bequest I ran that test with targets at 50, 100 and 200 yards. The rifle was a .308W with 10" twist. The bullet was 311291. The alloy was Linotype and all bullets for bot loads were cast at the same sitting. The bullets were visually inspected for defects and weighed to +/- .5 gr. Hornady GCs were used and Javelina was the lube. Two loads were used; first was a 1912 fps load at 136,000 RPM (in the top end of the RPM threshold). Second load was 2515 fps at 179,400 RPM (well above the RPM threshold). Ten shot groups wwere fired with each load at each range. The group size results were;

First load at 136,000 RPM; 50 yards-.7", 100 yards-1.3", 200 yards 2.5".

Second load at 179,400 RPM; 50 yards-2.55", 100 yards-4.7", 200 yards-14.5".

Obviously the group size was non linear with the load over the RPM threshold. I'll not post anymore here regarding this as Joe and 45 2.1 will just argue and argue. I think we answered M98s question and I wish him luck with both his rifles. I hope he posts back here what his results were. Thanks again for your input here Paul as it was most informative. I'll also thank Alberta Canuck for his input with obviously a very fine shooting rifle.

Larry Gibson

I'm anxious to hear back from him with his test results. Also hope he comments on the recoil. That's not saying he's recoil sensitive either.

I wouldn't compare high rpm 30 caliber cast bullet accuracy with large bore high rpm accuracy.

Joe

quote:

First load at 136,000 RPM; 50 yards-.7", 100 yards-1.3", 200 yards 2.5".

Second load at 179,400 RPM; 50 yards-2.55", 100 yards-4.7", 200 yards-14.5".

Very interesting test and results, Larry Gibson. Thanks for posting them here. (I am about to embark on cast bullet shooting with my 1902 Lee Enfield, which today, showed some promise of good long range accuracy with jacketed bullets. Now to learn how to handle wind and trajectory).

quote:

Let me give a brief example of how RPM above the RPM threshold adversely affects accuracy. I ran that test with targets at 50, 100 and 200 yards. The rifle was a .308W with 10" twist. The bullet was 311291. The alloy was Linotype and all bullets for bot loads were cast at the same sitting. The bullets were visually inspected for defects and weighed to +/- .5 gr. Hornady GCs were used and Javelina was the lube. Two loads were used; first was a 1912 fps load at 136,000 RPM (in the top end of the RPM threshold). Second load was 2515 fps at 179,400 RPM (well above the RPM threshold). Ten shot groups wwere fired with each load at each range. The group size results were;

First load at 136,000 RPM; 50 yards-.7", 100 yards-1.3", 200 yards 2.5".

Second load at 179,400 RPM; 50 yards-2.55", 100 yards-4.7", 200 yards-14.5".

Obviously the group size was non linear with the load over the RPM threshold. Larry Gibson

Quite representative for what you did and a good test. You could improve your results easily by using a mold in which the nose is large enough to engrave into the rifling. You've published your bore and groove specs for the rifles used and I know from John your mold is undersize. Get one that fits correctly and cut that large weight spread down to at least plus or minus 0.1 gr. or better yet no weight spread and you'll do better. A better alloy would help also.

45 2.1

I'll explain to you here as I did several times was that the test was not an attempt to achieve the most accurate load with those rifles. The RPM tests were to demonstrate the validity of the RPM threshold which they did. I did in fact use another mould that was a better fit (311466) and achieved very good accuracy out of 3 10" twist rifles with it well above the RPM threshold, 24-2500+fps. If you'd bother reading the 1st chapter I posted on the RPM tests You'd perhaps recall that the test was about Mr Joe average reloader not getting accuracy above 1900 fps or so with a typical nose riding mould out a a 10" twist '06. The reason was Mr. Joe average bullet caster/shooter was exceeding the RPM threshold which caused the accuracy loss. The tests were to, and in fact did, confirm that. Getting other moulds or a custo mould that "fit" is one of the ways I said, and demonstrated, that you could push the RPM threshold and get better accuracy at a higher velocity.

Thank you for this additional opportunity to explain. That is not a slam at you 45 2.1 as I'm sure there are some here who don't know what we're talking about.

Larry Gibson

quote:

Originally posted by Larry Gibson:
45 2.1

I'll explain to you here as I did several times was that the test was not an attempt to achieve the most accurate load with those rifles. The RPM tests were to demonstrate the validity of the RPM threshold which they did. I did in fact use another mould that was a better fit (311466) and achieved very good accuracy out of 3 10" twist rifles with it well above the RPM threshold, 24-2500+fps. If you'd bother reading the 1st chapter I posted on the RPM tests You'd perhaps recall that the test was about Mr Joe average reloader not getting accuracy above 1900 fps or so with a typical nose riding mould out a a 10" twist '06. The reason was Mr. Joe average bullet caster/shooter was exceeding the RPM threshold which caused the accuracy loss. The tests were to, and in fact did, confirm that. Getting other moulds or a custo mould that "fit" is one of the ways I said, and demonstrated, that you could push the RPM threshold and get better accuracy at a higher velocity.

Thank you for this additional opportunity to explain. That is not a slam at you 45 2.1 as I'm sure there are some here who don't know what we're talking about.

Larry Gibson

So here's what I'm getting from what you say and your test Larry. The rpm threshold is much higher (with accuracy) if you have a mould that "fits" (providing you're an accomplished cast reloader). Put another way you can't push bullets that don't fit or come from a bad mould. That in the end really doesn't point at an rpm threshold as the culprit.

Joe

Joe

That's not what I said. I suggest you go back over to the Cast Boolet Forum and look up the RPM threads. There is a detailed description there by me and others as to how to get the "best" fit and "bullet design" to be able to push beyonfd the RPM threshold. Mr joe average bullet caster gets a 311291 or any other regular commercial bore riding mould. He cast some up of recommended alloy, sizes the, .001-.002 over bore diameter, uses quality GCs and switches around with lubes, primers, and powders all at everyones advise. Yet when he shoots said trusty loads in his '06 with 10" twist his accuracy is always "good" up through 1900+/- fs but always gets worse above that velocity. He wants to know why he can't get good accuracy with that 311291 cast bullet out of his '06. The answer is RPM. Yes if he switched to a bullet that better fit (like Bass's LBT bullet or the 311466 Lovern) he may achieve "good" accuracy above the RPM threshold if he also does all the other things correctly. He is not going to get there with his 311291 bullet and RPM is the reason why.

Joe, I'm not going to rehash the whole issue here. It is already hashed and rehashed to death on the other forum, look there, the answers are there.

Larry Gibson

quote:

Originally posted by Larry Gibson:
Joe

That's not what I said. I suggest you go back over to the Cast Boolet Forum and look up the RPM threads. There is a detailed description there by me and others as to how to get the "best" fit and "bullet design" to be able to push beyonfd the RPM threshold. Mr joe average bullet caster gets a 311291 or any other regular commercial bore riding mould. He cast some up of recommended alloy, sizes the, .001-.002 over bore diameter, uses quality GCs and switches around with lubes, primers, and powders all at everyones advise. Yet when he shoots said trusty loads in his '06 with 10" twist his accuracy is always "good" up through 1900+/- fs but always gets worse above that velocity. He wants to know why he can't get good accuracy with that 311291 cast bullet out of his '06. The answer is RPM. Yes if he switched to a bullet that better fit (like Bass's LBT bullet or the 311466 Lovern) he may achieve "good" accuracy above the RPM threshold if he also does all the other things correctly. He is not going to get there with his 311291 bullet and RPM is the reason why.

Joe, I'm not going to rehash the whole issue here. It is already hashed and rehashed to death on the other forum, look there, the answers are there.

Larry Gibson

Larry,

So then my question to you is why would the two other bullets you mentioned be able to handle the rpm and get better accuracy?

Joe

Joe

They are less effected (adversely) by accelleration, they have short noses allowing better alignment between the axis of the bullet and the axis of the bore and the smaller lube grooves leave leave less room for unwanted setback and obturation. I also believe as bullets get harder (necessary to a degree for higher acceleration) larger lube grooves are conductive to small chunks of the driving bands being broken off by the rifling which unbalances the bullet. I've seen some evidence of that on recovered bullets but not enough to be positive about it. The less the bullet is adversely affected in the internal ballistic phase then the less adverse the RPM will affect them. Thus accuracy is sustained to a higher velocity level (the threshold is bumped) but at some point the RPM will still really denegrate accuracy. All of this is covered in the RPM threads on the other forum BTW.

You might be interested to know that recent tests have indicated that, with jacketed bullets, certain twists stabilize certain weights of bullets which gives better accuracy. This better accuracy is especially noteable at longer ranges. Thus it appears higher RPM can also have a adverse affect on jacketed bullets also. That is the subject of another thread on another forum here though. This is afte all, the cast bullet forum here.

Larry Gibson

quote:

Originally posted by Larry Gibson:
Joe

They are less effected (adversely) by accelleration, they have short noses allowing better alignment between the axis of the bullet and the axis of the bore and the smaller lube grooves leave leave less room for unwanted setback and obturation. I also believe as bullets get harder (necessary to a degree for higher acceleration) larger lube grooves are conductive to small chunks of the driving bands being broken off by the rifling which unbalances the bullet. I've seen some evidence of that on recovered bullets but not enough to be positive about it. The less the bullet is adversely affected in the internal ballistic phase then the less adverse the RPM will affect them. Thus accuracy is sustained to a higher velocity level (the threshold is bumped) but at some point the RPM will still really denegrate accuracy. All of this is covered in the RPM threads on the other forum BTW.

You might be interested to know that recent tests have indicated that, with jacketed bullets, certain twists stabilize certain weights of bullets which gives better accuracy. This better accuracy is especially noteable at longer ranges. Thus it appears higher RPM can also have a adverse affect on jacketed bullets also. That is the subject of another thread on another forum here though. This is afte all, the cast bullet forum here.

Larry Gibson

Larry,

I asked you that question to see what you would say. I have my theories like anyone would. I picked out a word you mentioned in the earlier part of your explanation and that is acceleration. To me that would be velocity. This leads me to believe the higher the velocity the more extreme the forces upon the bullet are when it's in the bore. This still tends to lead me to believe it's these forces, not the rpm that destroys the accuracy, although the faster the twist the more force put on the bullet trying to accommodate turning that fast in the bore.

I've had people tell me for the easiest success for shooting cast bullet the Loverins were the way to go, but I've also had them tell me that Loverins are not "the" style for high velocity shooting. To be honest I haven't tried push Loverins real high and currently don't have a loverin of caliber that has the capacity to try push it high. I do have int in 7mm but currently the only 7mm rifle I have is a 7mm-08 and the throat is much too short to seat the bullet out of the case capacity.

Joe

That is an interesting insight Larry Gibson, thanks once again! A 'twist versus accuracy' thread would be interesting!
Thanks for the 'direct' to the 'other' forum. (I haven't been there yet).

How do you folks size your cases for cast loading? I used to size normally but got the feeling the bullets were being damaged during seating. Now I do not size. I am trying a wad to seal the case then 'gueing' the bullet in place with 'waxy lube' and also seating in a soft, paper hand towel cup, again 'glued' with 'waxy lube'. I have not yet 'developed' my mould but have a few pistol bullets to try out. Now these only just protrude from the case mouth, so it will be interesting to see what the jump does.

Larry Gibson, may I ask what sort of peak pressure a cast bullet should be subject to if one is hoping for accuracy?

I have mentioned on another thread that I intend using lube-groove-less bullets, coated with 'waxy-lube' and seated over a lubed wad. These would be somewhat oversized to fit my rifle's throat, so would not need any case sizing. (Nor would they work from the magazine - the recoil would move the bullets in the neck).

quote:

Originally posted by 303Guy:
That is an interesting insight Larry Gibson, thanks once again! A 'twist versus accuracy' thread would be interesting!
Thanks for the 'direct' to the 'other' forum. (I haven't been there yet).

How do you folks size your cases for cast loading? I used to size normally but got the feeling the bullets were being damaged during seating. Now I do not size. I am trying a wad to seal the case then 'gueing' the bullet in place with 'waxy lube' and also seating in a soft, paper hand towel cup, again 'glued' with 'waxy lube'. I have not yet 'developed' my mould but have a few pistol bullets to try out. Now these only just protrude from the case mouth, so it will be interesting to see what the jump does.

Larry Gibson, may I ask what sort of peak pressure a cast bullet should be subject to if one is hoping for accuracy?

See 303guy, you're starting to ask questions that Larry won't totally agree on that destroy accuracy. That is you asked what pressure to load at. The real facts are that there are more then ONE thing that ruins accuracy....just not rpm alone. Don't get to hung up on Larry's rpm threshold.

Joe

quote:

Thus it appears higher RPM can also have a adverse affect on jacketed bullets also. That is the subject of another thread on another forum here though. This is afte all, the cast bullet forum here.

Larry Gibson

Then why bring it up in the cast bullet section? I also believe that's total BS unless you're talking about astronomical high rpms. There are just too many fast twist calibers shooting very small groups with jacketed. Of course you'll bring it down to extreme accuracy maybe such as bench rest shooters.

Joe

quote:

Originally posted by starmetal:

quote:

Thus it appears higher RPM can also have a adverse affect on jacketed bullets also. That is the subject of another thread on another forum here though. This is afte all, the cast bullet forum here.

Larry Gibson

Then why bring it up in the cast bullet section? I also believe that's total BS unless you're talking about astronomical high rpms. There are just too many fast twist calibers shooting very small groups with jacketed. Of course you'll bring it down to extreme accuracy maybe such as bench rest shooters.

Joe

Joe

Because of our pst offline conversations I thought you might be interested in what I found and would perhaps bring it up on another thread on "Reloading" perhaps. Apparently you're not interested.No problem with me.

Larry Gibson

quote:

Originally posted by Larry Gibson:

quote:

Originally posted by starmetal:

quote:

Thus it appears higher RPM can also have a adverse affect on jacketed bullets also. That is the subject of another thread on another forum here though. This is afte all, the cast bullet forum here.

Larry Gibson

Then why bring it up in the cast bullet section? I also believe that's total BS unless you're talking about astronomical high rpms. There are just too many fast twist calibers shooting very small groups with jacketed. Of course you'll bring it down to extreme accuracy maybe such as bench rest shooters.

Joe

Joe

Because of our pst offline conversations I thought you might be interested in what I found and would perhaps bring it up on another thread on "Reloading" perhaps. Apparently you're not interested.No problem with me.

Larry Gibson

Larry,

I am interested, put it in the appropriate thread please. I'm not sure which that would be, you pick I'll see your post.

Joe

303guy

Keep asking the question as yours are new and somewhat refreshing. Joe continues to have a hard time understanding. He can't seem to seperate internal ballistics from external ballistic. I'd bet Joe and I would agree 99 if not 100% on what damages a cast bullet during accelleration (accelleration occurs inside the barrel and is part of internal ballistics). What he has trouble with is comprehending the adverse affect increased RPM (above the threshold) can have on accuracy. The affect of the RPM occurs during the bullets flight or during external ballistics.


To your questions

"How do you folks size your cases for cast loading?"

I like to neck size well fire formed cases for cast bullet shooting in rifles. I use regular NS dies but also use Redding bushing dies for several cartridges. This allows me to tailor neck tension to a specific diameter of cast bullet.

"I used to size normally but got the feeling the bullets were being damaged during seating."

While not a question let me respond. If there is too much neck tension and /or not enough bell to the case mouth damage to softer alloyed bullets often happens. A bushing die to give .001-.003" neck tension helps as does a correct M-die. With bullets sized .311-.314 for use ing .30/.31 cal rifles I use a .31 M-die as th .30 M-d does not often times expand the case neck enough.

"may I ask what sort of peak pressure a cast bullet should be subject to if one is hoping for accuracy?"

There is a whole lot of "that depends" in that question. I hear a lot and have read a lot about a certain psi being maximum for cast bullet accuracy. Since actually measuring pressures of many cast bullet loads I no longer believe that. The alloy of the bullet, The design of the bullet, whether or not an adequate lube is used, whether the bullet just fits or is and excellent fit and of course how fast the "peak" pressure is reached (the time pressure curve) are all examples of things that affect the "peak" pressure ceiling for accuracy. There are other things too as I just listed several for example. I have one accurate load out of my 4" twist Palma barrel with a 311466 bullet that is way over he most often published max psi for cast bullet accuracy. I'm not at home now or I would give you some psi examples.

Keep us informed on your tests with the "lube-groove-less bullets, coated with 'waxy-lube' and seated over a lubed wad". That sounds like an interesting experiment and I'm quite interested in how you do.

Larry Gibson

I neck size for all my shooting except semi auto rifles. It's especially important to get a cast bullet started straight into the bore and rifling and neck sizing helps. I use all three styles: Redding bushing dies, neck sizing only dies, and the Lee collet dies.

Joe

[QUOTE]Originally posted by Larry Gibson:
303guy

Keep asking the question as yours are new and somewhat refreshing. Joe continues to have a hard time understanding. He can't seem to seperate internal ballistics from external ballistic. I'd bet Joe and I would agree 99 if not 100% on what damages a cast bullet during accelleration (accelleration occurs inside the barrel and is part of internal ballistics). What he has trouble with is comprehending the adverse affect increased RPM (above the threshold) can have on accuracy. The affect of the RPM occurs during the bullets flight or during external ballistics.


Larry,

That's the thing I and others you know don't agree on and NOBODY has proven it (well I take that back, many of us have shot accurately, very accurately with many different calibers at high velocity and high rpm) and you certainly haven't proven if it's damage in the barrel or rpm in the air. I certainly do not believe Waksupi's bending 6.5 cast bullet theory and so doesn't many others on the cast boolit forum.

Joe

Hi Guys, Don't check in here too often, but do find interesting things when I do.

Joe, you have my shooting of long projectiles at higher velocities, somewhat out of context. When I was doing that particular experiment, I was attempting to shoot pure tin bullets, at factory + velocities. This is where the bending came in.
I can not say what an alloyed bullet, at various hardnesses would do, when shot at those speeds.
Indications with the pure tin, was the bullets were indeed being twisted out of shape, as they left the the muzzle, resulting in at least a 15 foot pattern at 50 yards, and who knows what at 100.