rifle barrel twist rates

[LORD of WAR]

What's the best twist rate for a 14.5" and 20" barrel of an ar15? 1/7 or 1/9?

 

[drumenigma]

I suppose it depends on the ammo you are shooting. If you are primarily shooting typical 55g then the 1/9 is fine. If you shoot match grade ammo you'll probably want the 1/7.

 

[Skald]

14.5 I would go with the 1/7". Novekse, BCM, LMT and Troy predominantly use the 1/7 rate for their SBR rifles. Not the definitive answer but seeing what the manufacturers put on, esp. those that cater to the higher end of the AR platform is a decent place to start.

 

[Smiles1014]

Higher the grain - Faster the twist you want.

45-50 grain - 1/12 or faster
55-62 grain - 1/9 or faster
70 grain - 1/7

I forget where these suggestions come from, just seemed to pop in my head when i read your post. Logic is that the faster the bullet is traveling the more stability you'd want and the faster the twist the better the stability.

 

[RKG]

Higher the grain - Faster the twist you want.

45-50 grain - 1/12 or faster
55-62 grain - 1/9 or faster
70 grain - 1/7

I forget where these suggestions come from, just seemed to pop in my head when i read your post. Logic is that the faster the bullet is traveling the more stability you'd want and the faster the twist the better the stability.

Actually, it is "longer the bearing surface, faster the twist." There is a rough correlation between bullet weight and bullet length, but it is imperfect.

 

[LORD of WAR]

1/7 it is...1/7 will feed all grain bullets! thanx folks

 

[vellnueve]

I've actually been curious to see what 1/7 will do with a .22 conversion.

 

[Jose]

1/7 it is...1/7 will feed all grain bullets! thanx folks

Good choice.