I do not know any of the details of the blown up gun. I'm sure others may have later found out,, but it can often be caused by various things.
I know that many, many people shoot 9mm in USPSA competition safely. But when the USPSA started allowing the use of "9mm Major power factor" I had my doubts as to it being a wise decision. First off,, yes,, it can be loaded in a manner to make "major" easily,, AND safely.
But I have been around long enough to know that the one variable that can't be easily controlled is the human mind.
Loading a caliber like the 9mm to levels not found in manuals, or fully approved by SAAMI specs can result in problems. The 9mm is a small volume case, and is subjected to stricter levels of specs & components. Just a small amount of bullet seating depth,, or extra crimping can create a totally different pressure spike.
And when the human mind is involved,, sometimes,, without totally safe, well tested things,,, things can happen. Example; You load a "hotter" than the manual max load in a case. You fire a few and see no ill effects. A human mind may think; "I know they proof loads at 50% or higher for this,, so I should be ok!" Yet,, it's not usually the first,, or the 100th, or even the 1000th round fired that the problem rears it's head & proves to the shooter that they "did something wrong." In fact,, I've heard comments like; "I've used this load for a long time without any problems!" In their way of doing things,, they did NOT have access to pressure testing equipment,, NOR do they have the info on the actual metals used in their guns. Metal can accept a certain amount of excessive stress a few times,, but over time,, a well known thing called "Metal fatigue" can cause problems.
So,, when I teach reloading,,, I stress the fact that the manuals are published with LIABILITY in mind,, and that if the loads were not safe,, then the publishers could be held liable in a lawsuit.
I hate lawsuits.
But I hate injury or death even more.