I would recommend the APEX Duty/Carry AEK kit and the Reset Assistance Mechanism (RAM) to anyone carrying an M&P.
That said, if you are shooting other M&P pistols and having markedly better results, there may be some issue with the pistol. I would shoot it from a rested bench to make sure I wasn't sensitive to the snappy recoil of the .40 caliber, and if I wasn't able to group the gun I might consider sending it back to S&W to make sure there isn't something out of whack.
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