I've only ever run walmart winchester and federal in my JM. With that said it may not be the best sg ammo, but it does work. Around 300 rounds I had a disaster of a match with it. The sg wouldn't eject, didn't make it through a stag all day. I did some research after that match, and found that polishing the chamber may help. So I did it, wasn't hard, 10 mins with some metal polish on a cotton shotgun swab on a cleaning rod in a cordless drill. I took it out to the range at work and ran 100 rounds with no issues, then at my next match it ran with no problems. Hasn't had any problems since. (300 more rounds or so) hope that helps.