Common bullet grain

[Auburn1992]

Hey guys,

I was wondering if you guys could give me the best compatibility for twist rate and bullet grain for some common calibers. Some of the calibers that I would like to know are:

22 250--1 in 14"
223-----1 in 12"
243-----1 in 9" and 1 in 10"
7mm-08-1 in 9.5"
.308----1 in 10"

Thanks alot for any help!

 

[MTMilitiaman]

Bullet length is the primary concern when determining twist rate. Longer bullets require faster twist rates. It just so happens that heavier bullets in a given caliber are usually longer, but bullet style matters as well. Say you have a .30 caliber 1:12 twist barrel. It might stabilize a 220 gr RNSP, but probably not a 220 gr VLD or SMK, at least not in cold or otherwise thick atmospheres.

Velocity also matters. More linear velocity means more rotational velocity.

The .224 cal 1:14 and 1:12 twist barrels are primarily intended for relatively light varmint bullets, say 40 to 55 gr. They might stabilize heavier, depending on style and atmosphere, but a faster twist rate would be preferred. The 1:9 is the go-to for that caliber because it can typically stabilize everything up to 69 gr. The longest bullets, like the 77 gr OTM and Mk 262 rounds are generally recommended only with 1:8 or 1:7 twist barrels.

The rest of those twist rates look pretty standard. They should be able to handle most popular available options.

 

[CBS220]

MTMilitiaman has it down pat.

There is no definite answer, as bullet lengths and not weights have the largest effect.

 

[Swampy]

There is no definite answer, as bullet lengths and not weights have the largest effect.

Ditto......

YOu will need to check the manufacturers specs and recommended twist rate for each individual bullet against the twist rate of the rifle you are shooting.


Swampy