Re: Load for an AR 15
52gr Hornady Match and 52 SMK have shot the best out of my ar's. I have also had excellent results with both the 55gr Vmax and 55 gr Amax. I have not tried any of the Ramshot powders, yet. I've used mainly Varget and W748. Varget works great with my .223/5.56, .308, and .22-250, so that's what I use. I have a bunch of other powders I bought but have not tried.
I tried 60gr Partitions, but the best I could do was about 2.5" at 100 yards. They didn't group well in my .22-250 either.
BTW, the black rifle disease (BRD) is very, very addicting. I started with my Bushy Varminter, then it grew with my DPMS AP4 in .308, and then my first build (Spike's lower, Magpul CTR, YHM Forearm, & Bushy Patrolman's M4 barrel), and now I have a KISS (keep it simple stupid).