Southla1. I used the 1/12 220 gr. as an analogy. I have a Kimber in .223 that won't stabilize 60 gr. bullets, and I think it has a 1 in 12 twist. I can't seem to get the rod to twist when I try and check it. The jag holding the patch unscrews, rather than the whole rod turning.
The reason I brought up the 1 in 12/220 thing is every "egg-spurt" in the gun rags says that a 1 inj 12 won't stabilize a 220 gr bullet, and that the .308 won't shoot one (220 gr.) fast enough to do any good. My challenge to them is "WANNA BET?" I have gotten 2350 FPS from a Winchester Mod. 70 with 22" barrel, 1 in 12 twist, and very tight groups. This with both a post-64 push feed and a pre-64 Featherweight. I'll have to try it in a 1 in 10 twist .308 next, when I get time.