The AA base wad issue was real. It's been fixed in current production shells. We learned that loaders that do not use a primer seating ram from the inside of the shell such as MEC does could move the base wad while seating the primer. A very bad thing. I've loaded many thousands of two piece AA hulls including the initial run on MEC equipment with no issues. This possibility of a moving base wad exists with any shell that incorporates one. It's one reason I refuse to use hydraulic powered loaders. I want that feedback from the press to my human 'force monitor'.

The general rule is that a chamber blowout is caused by excessive load, and that a burst barrel further up is caused by obstruction. The obstruction leaves a 'ring' of some sort.

"The price of good shotgunnery is constant practice" - Fred Kimble