Ran some Federal 168gr BTHP M1A, and PMC Bronze 147gr FMJ ammo through mine, had a geissele SSA, KAC ambi saftey, LMT stock, KAC iorns, and a Vortex viper 2.5-10 FFP in Arms rings and was getting about 1 MOA with both, better groups with the PMC though surprisingly. Didn't open up more than 1.5 MOA at 100 yards and was able to hit a 5 Ft silhouette at 800m with the 168gr, all within kill zone for a battle rifle (slow fire). I was also initially running it with an AAC SDN-6 with a FL 51T mount, but it would have horrendous issues over gassing. I've heard they run with Surefire cans, but I don't own one yet.
The rifle should be better than 2-3 MOA though... I know two others who have bought em, one hasn't shot it, the other had no complaints, but I'll ask the one who's shot it what he was getting.
My Colt likes the lighter stuff for sure though.
Buy a cheap box of PMC Bronze 147gr FMJ and see what happens. Its cheap ammo too.