Lack of chamber support does not cause the bottom of the chamber to peel open like a banana. That's a double or triple charge there. And if you look at the majority of cases where the barrel was intact, a huge section of the case is ripped open, indicating that it was fired out of battery.
The real problem is that the striker spring directly opposes the recoil spring, so a brand new or extra power striker spring combined with a very old or reduced power recoil spring can result in disaster. A lot of the .40 brass I find that's been fired through other people's Glocks, has the firing pin indentation off-center, indicating that it was fired slightly out of battery, but not enough to harm anything (most of them don't even have the "guppy belly").
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Oh, and Tom, you may want to look into aftermarket refinishing of the barrel as well. Randy Ketchum can't replicate the tennifer finish, so the feed ramp, a small area of the chamber, and a bit of the underside will all be bare metal. Personally, I'm sending my barrel to Ron Mahovsky for Metalife chrome plating, after over a year of grumbling about the bottom area rusting (though the feed ramp and chamber interior never rusted, strangely, just that one little spot on the bottom). The price he quoted me is very reasonable.