This sounds nearly identical to a case I heard about back in 1984. It was a CVA. The barrel blew up and maimed the guy's left hand. If memory serves, it also maimed the guy next to him. My girlfriend was working as a paralegal in NYC and called me up to see if it passed my smell test.
It all sounded like doping a BP load with smokeless to me, except for one thing. In the 1984 case, CVA had bought out some bankrupt Italian firms' stock of barrels and then used them to make a batch of smokepoles with their label on it. The metallurgy of the barrel was in play the last time I heard about the case. I don't know how it ended. It made me swear off CVA permanently. Defect or not, CVA had no clue how the barrels were made.
