Possibly a bad moulding in the support polymer?, Squibb theory is very possible and primers are on center. Is that a bulge in the barrel ? Maybe the limits of ploymer have been found. One more pull on that trigger would have been ugly.
If those two casings are from the gun when the "problem" occurred, the finding of the "out of time cylinder" is a load of BS. I also agree with the squib load, then a live round down the barrel after that.I think it might have been cheap ammo that had a primer in it but no powder. The primer went off and had enough energy to drive the bullet out of the casing, where it got stuck in the barrel. A second round was then fired and the resulting overpressure caused the failure. If the shell casings in the photo were the ones removed from the gun it could not have been an out-of-battery problem because the primers are both hit dead center.