I originally posted this back in July, but since this topic is again being brought up, here it is again.
After reading about Glock KB's, I actually had one (actually, it happened to my wife, which is unfortunate, as she is just starting to shoot).
The Scenario: Glock 19 (not a .40 as is more common). Clean gun. Reloads, using 115 grn. jacketed (not cast) bullet, and a below max charge of 231.
The KB: Shot sounded normal, magazine was ejected from the gun. My first thought was that my wife had inadvertantly depressed the mag release. She said "That hurt, and I think that I'm done shooting now," but she didn't cry out or anything. Her hands had several burn marks where hot gas escaped between the frame and slide.
The damage: Minor burns to my wife's hands, and she is O.K. now. The little "foot" at the front of the magazine follower was broken off. The frame has a 1/2 inch crack on the right side.
The analysis: Most likely culprit is bad brass. The KB blew a 1/4 inch (approx.) hole through the brass at the rear, where the brass is unsupported. Glocks have the ability to fire while slightly out of battery, but this was not the case. Post-mortem on the case (chamber markings) show that the case was fully seated when fired.
While a bad reload is a possibility, it isn't likely. The brass was most likely Eastern European military, and likely obtained while an R.O. at a GSSF match.
The Bottom Line: Be careful out there! ALWAYS wear eye protection! (my wife was, fortunately). A high level of experience in reloading, coupled with very careful brass processing procedures will not guarantee that you will have no problems. It is possible for a weak piece of brass to get through, unnoticed.
Could this have happened in a gun with a fully supported chamber? Maybe, maybe not. Who knows? Just remember, that doing everything right may not always be enough.
Now before any of you start ranting and raving about "overpressure reloads" being the obvious culprit, ask yourselves how this could ever be determined, after the fact? After a round has been fired (and a kB occured), how will it be determined that faulty reloading and an overpressure reload occured? This is analysis I would love to see. Or perhaps your "analysis" is based on the following syllogism:
Glock is perfection.
A kB occured.
Therefore, faulty reloading MUST be the culprit. QED