I have 2 ARs, one is a Colt HBAR 1:9 twist and the other is a put together 18" 1:7 twist chrome lined. I loaded some normal 55 gr fmj. Nothing special, I think they are new mil-spec bullets. I know the 1:7 is better with heavier bullets but what kind of groups should I expect out of each of these guns with this non-match ammo at 100 yds? How much worse should I expect the 1:7 to shoot the 55 gr compared to the 1:9?