I shot a G17 today with an extended slide stop. Over half the time the slide failed to lock open on the last round. I'm almost certain it was my thumb riding the slide stop as I use a thumbs forward grip. So it looks like I'll have to pass on that upgrade. Not that I wanted to ever put one on mine anyways. Anyone else ever have this problem? I had this problem happen one other time to me on a Colt Mustang. I finally figured out what was happening after shooting it with one hand.