I have the Burris fixed mount, which works fine, I have heard of problems locally here with the QD Burris. After you switch that, think about other things. Did you do a break in procedure on the barrel when it was new? My current favorite for my AR10's are 39.6 grns. RL 15 behind a 175gr Sierra Match King in my 1 in 10" twist 16" barrel. Winchester primer, M118LR Lake City case. In my 1 in 11.25" twist 20" barrel rifle, I am using 41 grns. RL15 behind a 168 gr SMK BTHP, Winchester Primer, M-80 Lake City case. Not max loads by any means, but quite accurate.