[Bruce P.74]

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.

[JR]

When you insert the mag forcefully, the inertia is knocking the slide stop out of the arresting notch in the slide allowing the slide to come forward. This is commonly referred to as "a speed reload". A lot of shooters LOVE this!
You can replace the complete slide stop (spring may be weak). Also try replacing the recoil spring (more tension on the slide). If this does not do the trick, have the arresting notch (on the slide) cut a little deeper.