I find it interesting that the still-primed shell casing cooked-off like that. Also, that the shell casing on the opposite side of the cylinder appears crushed from compression, and then fragmented. Must have been some bodacious pressure waves involved in that miss-adventure. As is often said when things catastrophically burst in the old fossil plants: "Looks like the hoop stress done exceeded the yield strength"...hate it when that happens. (We say other things in the nuke-plants.) Also glad that nobody was injured. Thanks for posting. -S2