Thread: twist rates
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Old June 28, 2000, 09:49 PM   #3
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Dongun, the twist rate may improve accuracy but not trajectory, only the ballistic co-efficent or the velocity affects trajectory, that is unless the bullet is so unstabilized that it tumbles, then everything goes to hell in a handbasket.
As Chad mentioned the longer heavier bullets in a given caliber require a faster twist rate to properly stabilize them. In some calibers such as 30-06 a midway twist rate is chosen such as 1 in 10. It is not the best for the 110 grainers nor the 220 grainers but does a fair job on both, and the 1 in 10 is optimum for about a 150-170 bullet.
If a bullet is fired in a twist that is too slow it may tumble, in one that is too fast it is overstabalized and will remain in a nose high attitude and do other weird things, that is if it is not spun so fast at such a high velocity that it comes apart right past the muzzle. Some light .224 bullets designed for the 22 Hornet and fired in a 22-250 or a 220 Swift have this happen quite often. It is a combination of the over spin and velocity.

Carlyle Hebert
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