Stinger is the ultra high velocity 22lr. Case is longer for more powder. Pic just looks al. color.
Problem I have with your conclusion: If pressure is high enough to blow the SIDE of the case but front part isn't 'latched' into the chamber. Bullet DIDN'T exit barrel. I had a 40sw blow the head off, bullet exited and hit target good. Case was still in barrel. XDm is basically blowback with the barrel 'step' for a lock. Your powder is at the slow end of the chart. Could be part of the problem. Seen lots of PCC fired, even the 'ugly' one. No problems. Most of these guys are spray and play too. Not really my problem as I won't have one. And, yes, Mod 60 will go full auto if the disconnector is bad. At least until it jams.