"Ideal" twist/weight/velocity for .45 Colt rifle

[Snaketail]

Is there a formula to determine the "ideal" bullet weight and velocity for .45 Colt? I know my twist rate, my bore size - just need to know if I'll shoot a 200gr better or worse than a 250gr boolit.

I have a Rossi that lines .454, it has a 20"barrel and 1:30" twist rate - what would be the "ideal" weight for 1000/1200fps?

I suspect this has been asked before but I can't locate the thread - any help?

M

[Don McDowell]

That twist should shoot either bullet equally well, provided that the bullet fits the bore/groove etc. Velocity won't make much difference. Start low and work your way up, when the groups get to be what you want be happy.

[AJMD429]

There is a Dell formula that is an improvement over the Green hill formula. Look on the LASC website.

I think this is it...

http://www.lasc.us/Brennan_2-3_Twist.htm

(Look for the section titled "TWIST AND BLACK POWDER CARTRIDGE RIFLES")

[Griff]

All of my .45 Colt rifles are the standard Colt twist of 1:16, and shoot bullets from as light as 125 to 300 grains almost equally well, except for one rifle with one bullet. My 185gr WFN bullet doesn't shoot worth beans from my Uberti 1873 24" rifle. I can't say it will shoot worth a darn from any of the others tho', as due to its poor performance outta the 1873 I haven't bothered to test it in any of the others, (an Uberti 1860, a Browning 1885 or my Rossi 1892 Short Rifle).

What Don said. Formulas are nice... and can help you before you buy a mold... but... nothing beats actually shooting some from YOUR gun!

[CowboyTutt]

I've used the Greenhill formula a few times both in velocities as high as 2500 fps and as low as 1100 fps in my 71/84 Mauser. Its been right on the money every time. When I exceeded it with a longer bullet the load proved unstable. I've been reading this new book by McPherson called Metallic Cartridge Handloading-Pursuit of the Perfect Cartridge. I found a paragraph or two relevant to twist.

Gunmakers choose a twist rate according to various characteristics of the intended projectile. These include:

-Length--most important
-shape--important
-location of longitudinal center of gravity and aerodynamic force--a significant factor in long range stability.
-expected muzzle velocity--least important except for loads launching long bullets near the speed of sound, which often require a much faster twist.

Many small-arms projectiles leaving the muzzle traveling faster than about 2,000 fps will not remain accurate beyond that distance where velocity drops below the speed of sound. With such bullets, as velocity becomes subsonic, the buffeting from the collapsing shock waves initiate wild yaw fluctuations that continue until the bullet stops. Such wild yawing destroys accuracy.

This book is amazing by the way. It's going to be the "Holy Bible" of handloading for sure.

-Tutt