Well tried my faxon 308 heavy fluted AR barrel on aero upper n lower. 140 rounds of 168 fgmm, 175 fgmm, ppu 168. Best it will shoot is 2 moa at 100 yds in a lead sled. I changed scopes and mounts today and removed muzzle break. Shot another 80 rounds today and 1.5 moa one time the rest was same as yesterday all 2 moa. I am gonna take the barrel back off look at it good and retorque it and try again. If that dont work i am going to do what i should have done in the first place and buy a proof or bartlein.