I've been working with my gen4 and it stopped chambering rounds from any clip. Not sure how I fixed it but I cleared the mags of rounds, loaded in some snap caps and all the mags started working again. It was weird. When I saw it would rack one I ejected the clip and the slide was stuck. The slide release wouldnt release it, it just snapped back on its own. To be more clear a bullet never entered the chamber, it almost looked like it was stuck releasing the bullet. Right now it's cycling fine so I'm guessing something got stuck. This was after a field strip. I restripped it and put it back together and that didn't fix it. No clue but like I said its cycling fine now.