Barrel twist, vs barrel length dictates accuracy? What the??

[mstennes]

I have a guy trying to tell me that a 1/9 will stabilize all bullets in shorter barrels, he’s claiming 16” and less only need 1/9 to stabilize all bullets including 77 and greater. I always thought barrel twist had no variance on velocity? Barrel length does not dictate accuracy but velocity. Velocity doesn’t effect accuracy only energy down range, being that it starts to drop much quicker. Hes also claiming bullet coeffiecnt dictates twist? WTF?

[1168]

Bullet length, not weight determines the speed a bullet must rotate to acheive stability. Twist rate plus muzzle velocity determines what that rotational speed will be. So it is possible to need a faster twist with a shorter barrel. 1/9 is known to not always be fast enough.

[twm134]

I will second what 1168 stated. Bullet length dictates what twist is necessary for stability. Velocity and air density also have an effect on bullet stability. If anything a shorter barrel may need a faster twist to achieve bullet stability compared to a longer barrel.

[MegademiC]

You ate correct, barrel length in and of itself does not mean more accurate. In fact, all things equal barrels that are shorter are stiffer and tend to be more accurate, though its not always the case.

[gunnerblue]

High B.C. bullets tend to be longer, so may require a faster twist as already stated. This may be what your guy is talking about or the direction from which he is thinking.

[Todd.K]

Given the standard construction of most bullets we have come to talk about weight for twist stability. It is actually bullet length and velocity.

A long ogive match boat tail will need more twist than a short round nose bullet of the same weight.