Gents,
From time to time you get a guy posting about the intricacies of twist rates and acceptable RPM's for bullets at various velocities. I am hoping to attract anyone like that to this thread now.

The question relates to whether a 230grain jacketed bullet which stabilises well in a 1:16 twist standard 45 ACP barrel at say 900fps, will also stabilise in a rifle barrel say 20" long of the same twist now pushed 1500fps?

Is this velocity too fast for the twist/bullet lenght/calibre relationship resulting in over-stabilisation and groups deteriorating?

Its a mouthful but the guy who can answer the question, will know what I mean.

Feel free to offer an opinion anyone.

quote:

Is this velocity too fast for the twist/bullet lenght/calibre relationship resulting in over-stabilisation and groups deteriorating?

I don't think one can over stabilize. It is stable or it is not.

I have several pistol caliber carbines and shoot bullets a lot faster in them then any of my pistols.

Never had a problem with their accuracy.

quote:

Originally posted by p dog shooter:

quote:

Is this velocity too fast for the twist/bullet lenght/calibre relationship resulting in over-stabilisation and groups deteriorating?

I don't think one can over stabilize. It is stable or it is not.

I have several pistol caliber carbines and shoot bullets a lot faster in them then any of my pistols.

Never had a problem with their accuracy.

Well kinda!
I once many moons ago shot some 40grainers from a 22-250 and spanked the pig (well) past 4000fps. Long story short 8 out of 10 exploded 35-50yds in front of the muzzle and the last ones was so deformed they didnt hit the target.

quote:

Originally posted by The Dane:

quote:

Originally posted by p dog shooter:

quote:

Is this velocity too fast for the twist/bullet lenght/calibre relationship resulting in over-stabilisation and groups deteriorating?

I don't think one can over stabilize. It is stable or it is not.

I have several pistol caliber carbines and shoot bullets a lot faster in them then any of my pistols.

Never had a problem with their accuracy.

Well kinda!
I once many moons ago shot some 40grainers from a 22-250 and spanked the pig (well) past 4000fps. Long story short 8 out of 10 exploded 35-50yds in front of the muzzle and the last ones was so deformed they didnt hit the target.

It's my understanding that's the reason for the 22-250 having a 1-14" twist when Remington made it a factory cartridge. To prevent lightly constructed cup and core bullets from winking out of existence at high velocity.

As to the original question; in my non-expert opinion, I would find it difficult to imagine the 45 ACP could drive a bullet of any construction fast enough to cause problems.

quote:

Well kinda!I once many moons ago shot some 40grainers from a 22-250 and spanked the pig (well) past 4000fps. Long story short 8 out of 10 exploded 35-50yds in front of the muzzle and the last ones was so deformed they didnt hit the target.

Bullets that come apart are not over stabilized.

They are not structurally sound enough to take the rotational speed.

Take a mono bullet of the same weight and drive it through the same barrel at the same velocity and it well not come apart.

Let me sum up; you can successfully push your 45 acp bullet to any velocity you can possibly attain, from any twist made for a 45 caliber and from any length barrel. Period.
Not something to worry about.

Thanks fellas. Some of the cast bullet experts believe while overstabilisation is not as bad as understabilised the theory is over spinning short bullets accentuates any imperfections in the bullet/barrel/ etc and can double group sizes. And that a 1:16 twist in a 45 is getting close to that once you increase RPMS a bunch.

Hogfarmer you are most probably correct but just to clarify a 45ACP on a bolt action using 45 super brass can be pushed to almost double mil ball velocities. Maybe makes no difference-this is out of my expertise aka bigbores where every bullet has a sectional density of .300 or more

Ok, you just introduced another variable; cast bullets. Your original premise was with jacketed bullets.
Cast bullets are another whole list of dos and don'ts.

Didn.t the military use the same ammo in the 1911 as it did in the Thompson ?

Hip

quote:

Originally posted by dpcd:
Ok, you just introduced another variable; cast bullets. Your original premise was with jacketed bullets.
Cast bullets are another whole list of dos and don'ts.

No I didnt actually, but am responsible for the misunderstanding. The cast bullet guys as in 'cast boolits forum' were talking about jacketed bullets in this instance.

Hip; absolutely, same ammo in the 1911, Thompson, and M3 series SMGs. We had the 1911 and M3 on tanks when I started.

Tom:

What was the Thompson's velocity?

George

The thompson and other carbines were normal ACP pressures aka 21000 PSI and with the small powder charge usually 5-7 grains being burnt quickly, even from a carbine they were probably only scraping into supersonic levels.

The question relates to another 400-500fps velocity.

But Im not inclined to think it matters much. Bit of a false alarm from a few fellows on another forum. Thanks for the replies!

quote:

The question relates to another 400-500fps velocity.

I shot Jacket pistol bullets in my 460S@W at velocities a lot greater then a 45acp.


Will never even come close to no problems.

Load them shoot them.

If you really have to know what works with what... https://bergerbullets.com/twist-rate-calculator/

I don't know what the 45 SMG velocities are; we just fired them for qualification. Didn't seem much more than a pistol. I have shot them at 500 yards at a big pile of scrap vehicles; have to aim real high....
But for the OP, as everyone is saying, you needn't worry about shooting a jacketed 45 pistol bullet too fast. They will take any velocity you can possibly get out of an ACP case, and as stated too, some much larger ones.
I have a Bushmaster that I will test some out for you, when I get time. There won't be any problems.

quote:

Originally posted by p dog shooter:

quote:

The question relates to another 400-500fps velocity.

I shot Jacket pistol bullets in my 460S@W at velocities a lot greater then a 45acp.


Will never even come close to no problems.

Load them shoot them.

Thanks!

quote:

Originally posted by clowdis:
If you really have to know what works with what... https://bergerbullets.com/twist-rate-calculator/

Bergers calculator isn't really useful for the discussion, its testing for under stabilisation, not over.

I'd forgotten about all the longer case 45's out there like the 460, bushmaster and socom etc. My general knowledge jumps from 454 casull to the next near 45 cal being 458 win mag

quote:

Originally posted by dpcd:
I don't know what the 45 SMG velocities are; we just fired them for qualification. Didn't seem much more than a pistol. I have shot them at 500 yards at a big pile of scrap vehicles; have to aim real high....
But for the OP, as everyone is saying, you needn't worry about shooting a jacketed 45 pistol bullet too fast. They will take any velocity you can possibly get out of an ACP case, and as stated too, some much larger ones.
I have a Bushmaster that I will test some out for you, when I get time. There won't be any problems.

Thanks dpcd, but dont go to any trouble, I think the Bushmasters were usually 1:24 anyway, though some make references to 1:16 as well.

I started looking up reports on 460 SW encore with its 1:16 twists and fellas happy with 200 grain FTX so that is covering anything I was worried about.

I am no expert, but I have a Henry Big Boy steel .44 and the twist rate on it is 1 in 36" and that is way to slow! I have tried to get Henry to put a 1 in 20" or faster on it and they have no interest in doing anything! So much for their so called customer service!


Wayne

quote:

Originally posted by Karl:
I'd forgotten about all the longer case 45's out there like the 460, bushmaster and socom etc. My general knowledge jumps from 454 casull to the next near 45 cal being 458 win mag

Just for clarification, the Bushmaster utilizes the same .452 bullets the 45 acp uses. So dpcd could certainly push a 45 caliber pistol bullet with that cartridge. The 458 socom is a .458 like the 45-70.

quote:

Originally posted by hogfarmer:

Just for clarification, the Bushmaster utilizes the same .452 bullets the 45 acp uses. So dpcd could certainly push a 45 caliber pistol bullet with that cartridge. The 458 socom is a .458 like the 45-70.

Depends on his twist , I think the bushmaster was usually 1:24, though I read some 1:16 out there. If its the slower twist if he pushed them 50% faster I assume it would get the rame RPM as 1:16 for comparison. yup I knew about the calibres, why I said 'near 45's' just forgot half the near 45's there was lol.

But its all good, I am happy with the situation.
Thanks all.

This is another resource which I find useful: http://kwk.us/twist.html

quote:

Originally posted by Wayne74:
I am no expert, but I have a Henry Big Boy steel .44 and the twist rate on it is 1 in 36" and that is way to slow! I have tried to get Henry to put a 1 in 20" or faster on it and they have no interest in doing anything! So much for their so called customer service!


Wayne

And yet they use a 20" twist on their single shots.

Put an overly fast spin on bullet and it will impress a lot of folks as to how it kills game, but it also has a poor effect on penetration..As too fast a turn makes a bullet come apart in many instances...as to accuracy the really best way to answer the question is to try it out and see how it groups, I think its safe to say it can go either direction, the Red Gods of baistics do have a sense of humor I assure you..