I'm not a BT guy.........but do you know if the MM is in spec and cam timing correct ? Could there be anything out of adjustment ?

I have a hard time believing this too !! I helped a guy with a 27.5" HC Carbon 4 runner Extreme @ 63 lbs and he could only get 260's @ 5 grains per pound ! He only got 240's out of a regular HC 4 runner .......and he had 2 of those (one that came with a cracked riser and one with a warped riser from the factory) !! He was given the Extreme at cost because of the problems with the regular 4 runners !! I was less than impressed with his HC experience !!