I have been buying new replacement barrels for all my glocks(Federal, KKM, Fire Dragon) because of the chamber support problem in the older Glocks I have. Today I took a couple of the new one to the range and when I picked up the brass I noticed the bulge was not there. When I got home I cleaned the stock barrels and checked the chamber support with a few factory rounds. WOW, on the 9mm and 357 Sig, both new the chamber is fully supported, the G31 barrels has slightly more support in the 6 O'Clock position that my KKM. When did they change? I'm going to check out the new G21 and G20 I got last month and see if the same thing is there with them. Even the live round in the chamber has less movement than the older guns. This is great!