After watching this many times, It looks as if he starts to brace his left thumb on the cyl release. Possibly taking it slightly out of battery. BIKER13
what you think?
I would guess either a squib and the barrel blew up/off with one stuck in it prior to the incident.
Or could be someone shooting lighter loads with powders that are position sensitive. Titegroup was decent about not being position sensitive IIRC, but it's been a while since I made many light loads with things other than Trail Boss.