I knew you would show up if someone threw out a cookie.
The question in my mind is what factors are causing these pressure related issues? Is it easy to double charge the case due to the dynamics of case capacity and powder type? Is the neck area of the cartridge into which the projectile is crimped so limited that setback is more likely, even on a first chambering? (I have a very vague recollection of that being a potential issue, but even I won't rely on that memory.) Not my thing at all, like most lawnerds my background is more liberal arts type, and real physics is completely foreign to me, but there has to be some logical reason for these events. I get it if someone has chambered the same round a few times like a fool, but fresh ammo, first time chambered, from a decent manufacturer?
Another issue that is bothersome to me is that this is not common, somewhat random even, which makes studying it a pain in the ass, at least as to the Shield. On the other hand, I have seen enough reports of it on the S&W forum, with indications of poor response from S&W, that my risk management side's spidey sense is tingling. Too many questions, not even enough hints of answers.