I recently bought a used M&P45 for training purposes, to suppliment my duty M&P45. I have fired approx 500 rds through it thus far, though I don't know how many the previous owner put through it. What I immideately realized was that while the pistol extracted perfectly fine when shooting, when I tried to manually extract a round (by pulling back on the slide), it would jam as the round would not come all of the way out of the chamber. Does anyone have any insight as to why this would be happening? Obviously this does not happen with my other M&P45 FS or my M&P45c. Thanks.