Lumberjack98 wrote: The gunsmith says that if the primer was not set properly, that it might be possible for the forceful closing of the cylinder to cause the primer to ignite.
Bingo!
A "high primer" can also be a source of a "jam" in a revolver.
Its odd that the cartridge bore in the cylinder lined up with the forcing cone at the exact same time the cylinder closed and the primer ignited.
It could happen though.
Always inspect each round of ammo for telltale signs of poor construction. A "high" primer would have been easy to spot.
Generally, factory fodder is excellent, but I still cycle each and every round of my defensive ammo before trusting my life to it.