I have a B.A.D. on my Long-Range AR, and I am experiencing almost the same problem, with almost every shot. I shoot an 80gr bullet loaded short with an MV of about 2780 fps. I have narrowed the problem to one of two factors:
a) higher than normal bolt carrier velocity due to the higher pressure load (no signs of excessive pressure), or
b) weak magazine that can't counter the weight of the M.A.D., bolt latch, and S.L.E.D.

I am leaning towards the magazine spring being weak. I am looking for a stronger spring for a short 5-8 round magazine.

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Judge control not gun control!