Originally Posted by AustinTx
I have fired factory 45ACP in a Colt 1911A1 and a Glock 21, with very different results. The cases fired, in the Glock had such a big bulge they wouldn't go in a re-sizing die. The very same ammo was fired in the Colt with absolutely no indication of anything amiss. It was commercial Remington FMC, 230gr, 45ACP ammo.
The original Glock was designed for the 9x19, a tapered round. Glock 9x19 chambers are nice and tight. The tapered cartridge feeds very well.
When they had to adapt their pistol to US cartridges, they had to deal with straight wall cartridges such as 40 S&W, 10mm, 45ACP. To assure reliability they went nuts with the chambers making them loose and without the support we were used to. Putting a round in the barrel of a G21 and looking at the bottom reveals the problem, no support. The 45 is their worst. If it was not for the low pressures of the 45, every single round would be a KB.
I cannot understand why the US manufacturers keep designing straight wall semi auto cartridges when a little taper can make them feed so much better and can use a tight chamber.