Quote:
Originally Posted by apollo99
Generally speaking 1:9 good for 55 grain 1:8 55-62 grain 1:7 62 grain and up. That's not to say you can't shoot any grain out of any twist barrel, but there is an optimal twist for a given bullet weight for stabilization. I'm giving a very simplistic version of this.
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I always wonder why the Internet tends to generate grossly overspinning bullets, especially in .223.
A 55 grain flatbase spitzer has been stabilized by a 14 twist with excellent accuracy for several decades now, certainly the 1958 .222 Magnum the .223 is based on and no doubt a bunch of earlier wildcats.
The Pentagon found a 12 twist needed for the 55 grain boattail in cold air.
The 62 grain SS109 partial steel core bullet does just fine in a 9 twist, as do some 75 grain lead core bullets.
The only thing in general use that demands the fast fast fast 7 twist of the M16 and M4 is the very long tracer bullet.
Target shooters debate over the advantages of the 7.5, 7.7, and 8 twists for their 75-82 grain boattails.
Barrel life depends on what you are calling "life." Shoot at tin cans and foreigners at moderate range... 10000 rounds. Shoot for X count at 600 yards, maybe 4000. Shoot for the small X ring of the F class target, maybe 2500.