All of you would be experts miss the major error here. The guy had an unusual discharg and did not, since it was not a combat situation, fully inspect the weapon and fired the piece with an obstructed bore. It is amazing how easy it is to load a .40 in a .45 mag. I did it myself on my private range. After the unique discharge, the weapon was cleared and inspected. In my case the extractor pulled the ruptured .40 case out of the chamber and no damage was done to the gun.
You left off the "sarcasm" tag.
If you were not being sarcastic then either stay on your "private range" of sell your guns.
Anybody who does not inspect their ammo before loading it into a weapon is dangerous and should be unarmed.