A very interesting analysis of the Glock KB issue was done by Mark Passamaneck, a forensic engineer who investigates "accidents and failures for a living." His work is available in two places (that I know of); an article on the GlockFAQ website and a chapter in the excellent second edition of Robin Taylor's book, The Glock in Competition.
He blew up his Glock unintentionally, blew some up intentionally under laboratory conditions and examined others which had blown up.
Like WalterGA, Passamaneck makes a clear distinction between case failures and barrel failures. On the subject of "unsupported" chambers, he writes:
"The loose, partially unsupported chamber has attracted a lot of the gun store commando spotlights in the past few years, but the chamber dimensions, in and of themselves, will not cause a KB. Additionally, case failures exhibit a very different failure mode than gross overpressure....Case failures rarely damage the slide or barrel. Sometimes magazines, triggers and mag releases are liberated, but usually a few bucks in parts puts them back together again. The pressure vents downward through the front part of the grip...."
In contrast, "[t]he damage and potential injury due to a barrel failure is quite different. Barrel failures are caused by gross overpressure. Obstructed barrels, double charges, deep-seated bullets and severe leading can be responsible for gross overpressurization."
He continues "Of the several dozen blown Glock barrels I have personally been involved with reviewed injury reports from, the worst injury besides soiled shorts and bruised confidences are blood blisters and a sprained finger here and there....[t]here was not one slide separation and not one grenaded chamber. I cannot say that for other blown guns I have examined. A blown Beretta or a blown 1911 can severely injure the shooter. The chambers on most other pistols are round on the exterior, so there is not a predictable failure location....Good engineering design incorporates predictable failure locations and modes. Glocks are very strong indeed. If I was forced to fire a double-charged or otherwise excess pressure round, I would choose a Glock to shoot it in every time."
Passamaneck has much more to say on the topic of this thread and I commend his chapter in the Robin Taylor book to your attention.
Bottom line: the generous chamber dimensions of Glocks, particularly in larger calibers, may make them more prone to case failures but DO NOT make them more prone to blowing up barrels!
A forum with WalterGa is a more informative, funnier, and more interesting place.
G17, G17RTF2, G19, G21, G21SF (2), G26, G30, G30SF, G34 (2), G37 (2), G38, G39