It's widely known that the chambers of Glock .40S&W barrels are not fully supported, and that part of the cartridge case will bulge where it's not supported by the barrel. This is actually true. Depending on who you ask, this could be a problem for reloaders. Not all reloaders agree that .40S&W Glocked brass is the problem that so many claim it is though. I don't have a .40 Glock, or any other .40 for that matter, so I can't tell you from experience.
The Glock .45ACP barrels also have chambers that aren't fully supported. I do see some bulging, but the Lee dies iron that right out. I've fired Glocked-brass reloads through a Kart Match barrel and a Kimber barrel without a problem, and they all drop in and fall out of the EGW gage block. I know I've got .45ACP brass that I've fired through my Glock 21 at least 6 times, and I've never had a .45ACP case fail yet.
I can tell you for sure that the chambers of 9mm Glock pistols are as supported as you're ever going to get for a 9mm autoloader. No bulged brass, no problems. I run Glocked 9mm brass through Lee dies, and then run the ammo through Kahr, KKM Match, RRA, Smith & Wesson, or Beretta barrels. I don't even use the Lee Factory Crimp Dies for pistol rounds that re-resize rounds. I've probably got brass that's been fired through my factory-stock Glock nines 6 times, and I may reload this brass a few more times before I lose it. The only brass I've ever cracked was nickel plated Federal, and that let go after 2 or 3 loadings.
If you're still concerned, and you've got any Glocked-brass that you want to sell dirt cheap, let me know.