conicals in slow twist

[.50cal]

I have 2 guns with 1:60 twist 1 is .54 the other is .58. I was going to order a couple moulds like REAL mould for thr .54 and a mini for the .58. Or should I just stick with Round balls.....Thank you in advance

 

[cowpoke1955]

I have two .54 cal. GPRs (one flint and one percussion) and never had any luck with the REALs. I tried the 300 grain and the 380 grain. My GPRs are tack drivers with round balls out to 100 yards. A .54 caliber ball will take care of anything in the good old USA. I do have very good results with the 380 grain REAL out of my T/C Hawkens and its 1 in 48" twist barrel. Others have claimed to get good results with the REALs out of their GPR. Maybe someone else can speak up. Good luck :thumbsup: .

 

[MSW]

there's a relationship (no doubt a mathematical formula somewhere) between the rate of twist, the wieght of the projectile, and the velocity. as a general rule, heavier projectiles require a faster rate of twist. then add in barrel harmonics, ambient temperature and humidity, heck, the phase of the moon is probably in there somewhere...

the long and the short of it is that you will most probably have poor result trying to stabilise a heavier projectile with a slower twist. note that i said 'probably...' really, there's only one way to find out, but when you try, don't be terribly upset if the rifle won't do something it wasn't really designed to do.

 

[Bountyhunter]

The long and short of it is that longer/faster projectiles require faster twist, and shorter/slower projectiles require slower twist. The longer and shorter is in relationship to bore. Longer is heavier, yes, but the formula is a function of diameter and length.

 

[AZ-Robert]

there's a relationship (no doubt a mathematical formula somewhere) between the rate of twist, the wieght of the projectile, and the velocity.

It's the Greenhill Formula. As BountyHunter says, it's the length of the projectile rather than the weight (though they are related). Scroll down to the bottom of this page:
http://members.aye.net/~bspen/math.html

.

 

[paulvallandigham]

Please note that the Greenhill formula was calculated for cast bullets, and a velocity near 1500 fps. If you are shooting them at a much different velocity you need to know this fact, and make an adjustment to get optimum performance.

The multiplier- 150 - in the formula correlates to that 1500 fps velocity.

If you were shooting a cast bullet at 1800 fps, change that multiplier from "150" to " 180 ". Run both formulas and you will see that even this change does not require much difference, if any, to the length of the bullet. That is why the typically pubhished Greenhill formula uses the 150 as the multiplier, without this other information.

Note, however, that with some of the larger caliber " Sharps " rifles, reaching even 1500 fps with a black powder load and some of the long bullets is next to impossible, and many of these guns generate velocities in the 1200 fps range or less. Because of the recoil, trying to get more velocity is abusive to the shooters. IN the old days, ( 19th century) " Express " Cartridges gave these Black Powder bullets more velocity by adding a bit of length to the casing, AND reducing the weight of the bullet.

For instance: The .45-90 was considered the " Express " version of the .45-70 cartridge. The .45-90 had more powder, but shot a 300 or 350 grain bullet. The .45-70 shot less powder, and either a 500 grain, or 405 grain bullet in its factory loadings. Both cartridges were fired from rifles with a 1:22 ROT, so the Greenhill formula was pretty much ignorred in using those shorter, lighter bullets in the Express versions. The Express cartridges were not sold as better long range target ammo: instead, they were sold like " magnums " are today- reputed to have greater " knock down " power!! :shocked2: :rotf: :surrender: :thumbsup:

 

[tg]

"Or should I just stick with Round balls.....'

There is nothing I can think of in N.America that the PRB in the cals. you have that a PRB will not easily take, there is real no need to use modern bullets.

 

[BrownBear]

I have 2 guns with 1:60 twist 1 is .54 the other is .58. I was going to order a couple moulds like REAL mould for thr .54 and a mini for the .58. Or should I just stick with Round balls.....Thank you in advance

I've got more curiosity than is usually good for me, so I have to try things to see for myself. I've tried both the heavy and light REALs in my GPR 54. I don't remember the weights off the top of my head at the moment. The heavy one was a stinker at any range. Groups ran 6-8" at 50 yards. The lighter (and shorter) one turned in 3-4" groups at 50 yards, sorta do-able, but nowhere good as RBs. But at 100 yards I couldn't keep them on the target paper from a gun that will really lay in the RBs at the same distance. I've heard folks doing fine with Buffalo Ballettes, but I haven't tried them in my GPR.

Based on other experiences, I'm betting if you could push the short REAL way up near max, velocities and rate of spin would be high enough to stabilize it better. But as velocities dropped the accuracy would go with it.

For me that all kinda defeats the whole purpose behind a conical- longer range shooting. At closer range there is probably some benefit in penetration on large game, but I haven't felt the need with my 54s and 58s. The RBs are fine. If I was to take on moose with a 50 I'd be shooting a conical, as I would if I was inclined to take long shots past 100 on any game.

Just my way of looking at my rifles. Doesn't mean I'll think you're a traitor to any cause if you want to switch to a GPH barrel so you can shoot conicals from a GPR. That's the way I'd do it too, if I felt I needed them.

 

[Blizzard of '93]

according to what I've read concerning the REAL (I use 'em in my .50, 1-48) Lee advised 1-48 or faster twist.

 

[brubincam]

-----just put them in and try them-----

 

[renovato]

About the only conicals I've had much luck with in slow twists are the short ones like the Ball-et. If you drive them fast enough, you can get them to stabilize pretty well.

All in all, round balls are cheaper to shoot, generally more accurate in slow twists, will take any game you intend to hunt on this continent and don't lead your barrel like a conical does.

 

[gmww]

I've been lucky enough to be able to shoot hunting sized groups using the maxi-ball in my slow twist .45. About 4" at 80 yards. I don't think they are stabilized enough as I can see a very very slight oblong hole instead of perfectly round.