How slow of twist can a guy get away with....338 lapua...300SMK. I have a friend who has an AR 30, and we have it shooting great with 250SMK's. I am itching to try a 300 SMK in it, but don't know if it is worth the effort. I think the AR 30 has a 1-12" twist, but I could be wrong. I haven't seen the rifle for a while, but if I'm not mistaken we had to seat the bullets a little deeper than I like due to mag length restrictions. Anyone try the 300SMK in an AR 30??