BARREL LENGTH AND TWIST RATES DISCUSSION
Posted: Sat Nov 24, 2012 10:01 am
Hey guys, I did see this briefly discussed in another thread, but wanted to have a longer discussion about it. I know this might be somewhat of a black art, but I wanted to know your thoughts on barrel length and twist rates.
I'm leaning toward Mcgowen to build this barrel.
Bushmasters twist rate on the AR barrel is 1:24. This is a very accurate barrel from the get go, however out of a bolt gun, you have some more flexibility in developing loads. and to tailor to suit specific needs.
Twist rates for the 45acp, 45LC, 460 SW, 450 marlin, 458WM range from 1:14; 1:16, 1:18.75, 1:20, 1:22, 1:24.
the Greenhill equation (twist calculator) gives me an impossibly long 1:40 to 1:64 twist rate depending on load. (smoothbore!)
With these twist rates, now barrel length comes into play. What are your guys thoughts on the correct length to fully stabilize a bullet?
Powders used on the 458WM look like they go as slow as Benchmark for 300gr bullets, and Varget in the 350gr arena. Which should be fully burned by probably an 18" barrel with that heavy of a projectile.
I would be under the impression that a for me primarily shooting 300grainers @ max of 2400fps- 1:20 or 24 twist with a 24" bull barrel might be the best choice.
And even before I get started with this build exercise, Tim, any idea on where to find a Legendre Magnum reamer?
I'm leaning toward Mcgowen to build this barrel.
Bushmasters twist rate on the AR barrel is 1:24. This is a very accurate barrel from the get go, however out of a bolt gun, you have some more flexibility in developing loads. and to tailor to suit specific needs.
Twist rates for the 45acp, 45LC, 460 SW, 450 marlin, 458WM range from 1:14; 1:16, 1:18.75, 1:20, 1:22, 1:24.
the Greenhill equation (twist calculator) gives me an impossibly long 1:40 to 1:64 twist rate depending on load. (smoothbore!)
With these twist rates, now barrel length comes into play. What are your guys thoughts on the correct length to fully stabilize a bullet?
Powders used on the 458WM look like they go as slow as Benchmark for 300gr bullets, and Varget in the 350gr arena. Which should be fully burned by probably an 18" barrel with that heavy of a projectile.
I would be under the impression that a for me primarily shooting 300grainers @ max of 2400fps- 1:20 or 24 twist with a 24" bull barrel might be the best choice.
And even before I get started with this build exercise, Tim, any idea on where to find a Legendre Magnum reamer?