I just purchased the Shield Performance Center 9mm and this happened to me on the range today. I got through 2 clips and the slide locked up and I could not get it to move forward. Very disappointing and worrisome as I purchased this to be my carry gun. Got home and somehow got the slide to move forward so field stripped. It does seem like Rastoff's post might be on to something since the slide was really stuck and I could not get the slide to budge at the range. Seems to be fine now so will hit the range again this weekend to see if it happens again.