One of my uppers is A 1/7 krieger 24" depending on the yardage im shooting i use anything from 69gr to 90gr I use sierra MK69,77,80,90, hornady A-max/bthp(mch)68,75,80 ,nosler custom comp69,77,80, lapua Scenar70.The bulets I seat close to the lands they all differ, you just have to see what your barrel likes the best charge and OAL any of those I named will shoot great but if your looking to be consistent with small groups that's work nobody can tell you, you have to do your homework. At 100yds I personally think its pointless shooting heavier than A 69gr bullet, your (rifle) can shoot under 1/4minute consistently if you find the right load. The reason I use all these bullets is because I just started loading A few months ago and each one of my AR's likes something differant along with all the variations and variables.