Joe, why don't you list all the barrels that burst for no apparent reason you have personally seen. You sound like you have quite a list. I know of one. It's because I loaded 94grs of PB by mistake. I thought I had Pyrodex in the bottle, and it took 4 shots - station 2 on the skeet field. Blown chamber & 23 stiches on my forearm. I had the shells tested. They were 23,500psi. The gun was a 1889 Remington twist barrel hammergun. I even sent the barrels to some place in California for testing, but never hear anything back. Any type of barrel blows in the chamber because of too much pressure, down the barrel because of a obstruction. I could be wrong but these look like the chamber blew.