9mm, picked it up a month or so ago. Had a problem with the bullets rotating nose down and jamming on the feed ramp (HP). Not so much a problem with ball ammo. I put some S&W style followers in the mags and lessened the feeding problem, but still not 100% with HP, almost 100% with ball. I've got to polish the feed ramp and check the mag lips to see if that helps. Nice gun, like the feel of it, hope to be able to get it up to reliable enough for carry and not just range toy status.
If you're not taking flak, you're not over the target.