The 69 Sierra MatchKing is a proven bullet in the 1:9 223. I have seen several that shot that bullet well. I have only tried one 1:9 with the 75 AMax. It worked ok. Didn't group near as well as the 69SMK so I didn't play with it much more. Friend has a 10FP in a 223. His wouldn't shoot the 75AMax well at all, but his loved the 69SMK. Lots of guys will use the 77 SMK for distance (FClass). That is what I am using with my son for his FCLass rifle, but it is a 1:8 twist. Luck in your choice. Tim