I'm having the same issue in both cals. In 380acp I'm shooting both jacketed and cast round nose style bullets. They have very similar weights and profiles. However, the jacketed are shooting ok, and the cast is hanging up just out of battery. I've checked mouth size, looked for bulges and made sure that single shots lock the slide back. I "plunk" test them by dropping them in the bbl and making sure they chamber, I hand cycle them and they cycle fine, but as soon as it's live shooting, I'm getting constant failure to feeds, a good smack on the slide seats most of them. On ejection, I'm getting damage around the back edge of the bullet where it looks like it's contacting the rifling. Worst part is, the EXACT same issue is happening in 45acp. I'm thinking maybe the bullet is yanking forward on chambering and ramming into the lands? But other than that, I can't for the life of me figure out why they would only do this on firing and not on hand working the action. I tried seating them deeper but got to some pretty silly depths with the same issue. Maybe my bullet is a bit too fat (.356 in the 380) and the leading edge is catching the end of the chamber? But I would think hand cycling would show that.. Any ideas cause I'm at a loss.