Dogger,
On July 20,1998, I experienced a case head separation involving a .40 S&W 155g Fed. H.S. while chronographing various standard pressure factory offerings out of my G-27. It was the 6th of 7 rounds of that particular load. The barrel was clear; the chamber was clean and the Glock was fully in battery. Interestingly, the incident bullet yielded a vel. of 956.7 fps compared to an avg. of 1090 fps for the preceding five rds...obviously most of the gases headed in the correct direction. The round had a muffled report, some quantity of gas was expelled through the grip frame and the action was difficult to clear due to brass deformation. The Glock suffered no apparent damage. The incident was documented and reported to Fed. and Glock in detail (incl. photos & cartridge case components). Both companies proved to be extremely responsive and helpful. Bottom line...brass defect x 1 and a generous chamber.
I have been extremely fortunate, as a shooter,competitor and reloader for 45 years this is the first malfunction of any kind experienced with any firearm or component. Do I still own and shoot Glocks? You bet! Do I worry about Kb's? Not at all! Do I pay attention to the details that all of us should "hawk"? Absolutely!
Enjoy your Glock, Dogger.
Bill