So, I was at the range shooting some Rem UMC FMJ 115gr and also trying out two boxes of CorBon JHP 115gr. First magazine of CorBon was fine, no problems. On the 11th round of the second CorBon magazine the slide locked back and a round did not chamber from the mag. I tapped the bottom of the magazine, dropped the slide and it chambered fine. I then cycled the slide to eject it and placed it back in the magazine. It chambered fine the second time around. I also noticed on the CorBon cases there was a flat spot on the rim of the case after being ejected. Any insight into the issue? I had no problems with the 150 or so Remington rounds I used that day and the cases looked fine after being ejected. Thanks for the help GT!