I was using my G19 in a CFS class, and had a bunch of problems with the reloading from slide lock. after inserting a mag hard and fast, on multiple mags, the slide would slam forward on its own, causing me too have to do a tap rack to make sure it was loaded. (per curriculum) what the heck is causing this, and how do I fix it, without babying it? The mags are all the same vintage, and usage. We were doing this under pressure so I couldn't figure out if some, or all the mags were doing it. Any help would be appreciated.