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Bart B. · December 20, 2012, 06:12 PM

1:12.

That's based on the benchresters favorite twist for 50 to 55 grain bullets fired at the same speed as the .223 Rem. does is 1:14 made popular with the .222 Rem. years ago. With the shorter AR barrel, one needs a slightly faster twist to spin the bullets at the same rpm rate.

Check out http://www.6mmbr.com/223Rem.html

Spinning bullets too fast will shoot those unbalanced ones too far away from group center. The faster a given bullet is spun, the more centrifugal force there is to make it jump off the bore axis as it exits the muzzle. Best accuracy is attained when the bullet is spun just fast enough to keep it stable all the way to the target. 1 grain less powder may not spin it fast enough to do that.

December 20, 2012, 06:12 PM	#5
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	1:12. That's based on the benchresters favorite twist for 50 to 55 grain bullets fired at the same speed as the .223 Rem. does is 1:14 made popular with the .222 Rem. years ago. With the shorter AR barrel, one needs a slightly faster twist to spin the bullets at the same rpm rate. Check out http://www.6mmbr.com/223Rem.html Spinning bullets too fast will shoot those unbalanced ones too far away from group center. The faster a given bullet is spun, the more centrifugal force there is to make it jump off the bore axis as it exits the muzzle. Best accuracy is attained when the bullet is spun just fast enough to keep it stable all the way to the target. 1 grain less powder may not spin it fast enough to do that.