I'm glad you're unhurt! That's what matters most.

It's too bad you were unable to find the piece(s) of metal that blew out of the cylinder. My guess is that Smith would want to look at all of them in order to determine whether there was some structural failure in the cylinder rather than overpressure. I'm thinking that, possibly, some weakness in the cylinder wall, perhaps a microscopic crack, might have accounted for the blowout rather than an overloaded round. On the other hand, those blown out shells are suspicious.