Since I purchased my SP2022 a few months ago I've put ~750 rounds through it with no problems. Yesterday at the range, after the last round in each mag, the slide wouldn't lock back. I was shooting Winchester 9mm NATO and then switched to Speer Lawnman 124gr. It didn't matter what mag or ammo combo I used, the slide wouldn't lock. Any ideas on the question? I thought shirley the mags were to blame but I doubt I have 3 bad mags that are basically new.