"Federal Top Gun hulls have a fiber base wad. I have heard reports of this wad separating and lodging in barrels but have never experienced it."
I am curious about this statement. I hand load and use fibre base wads in all my loads. Upon exiting the barrels they do separate and I can find pieces spread out across the range, but I'm not sure what is meant by separating in the barrels and lodging enough to create an obstruction? Is that a squib load? I also wonder what type of fibre base wads Federal is using that more than one person here has first or second hand experience of separation issues?
"Any chance he had a 20 gauge shell in his pouch?"
Judging from the placement of the blowout from the breach that would have been my first question.