I actually rip the mag away when I do a reload on the Glock. I'm a lefty, but here is the process: press mag release with trigger finger, right hand slides down and grasps base of mag, mag is ripped out and dropped on the floor, right hand continues downward movement to mag pouch to complete reload.

Good news is that the mag gets out of there everytime BEFORE the new mag gets to the weapon; no stripping a mag out with a full one in your hand. Bad news is that it's just a little slower.

I had a G23 that would either fail to lock back sometimes, or would release the slide when I put a mag in too vigorously. It always grabbed a round, but I never trusted that it would every time. So, I enlarged the slide stop notch in the slide and gave it a slight rearward angle so that it made a very shallow hook. This solved the problem. Haven't had to do it on any of my 9mm Glocks.