There you go. Heavier BCG works better. If your buddy doesn't want to change out the BCG he can go for a heavier recoil spring and/or a heavier buffer and see if that will work. It is a balancing act between the amount of gas driving the action, the weight of the BCG, buffer weight and spring. I'd suggest a heavier buffer as the best easy fix, changing the spring rates seem to add a factor of ammo sensitivity.
HTH
ETA arfcom is the place for AR knowledge. You can find tons of good information in the stickies in all of the technical forums. Just stay our of the general discussion area, where no amount of idiocy is too much.
