TexasCHLforum.com

One of the reasons that Glock developed the .40S&W Gen 4s first is so that they could address the issues seen in earlier models chambered in .40S&W. To my knowledge the Gen 4 Glocks do not suffer from cracked frames when chambered in .40S&W any more than Gen 3 models chambered in 9mm.

When shooting factory ammunition the unsupported area of the Glock chamber is not an issue. The unsupported area becomes an issue when shooting reloads, or trying to reload brass fired from the Glock Pistol. Comparing the unsupported chamber in a .40S&W Glock to the unsupported Chamber in a .45 1911 is like comparing Oranges to Lemons, and only valid if you are considering that they are both citrus. The .45 ACP is a low pressure cartridge and the .40S&W is a high pressure cartridge. Reloaders usually have no issues with .45 brass fired 1911s, and other .45 ACP handguns while there is a vibrant market for "Bulge buster" and aftermarket barrels for reloaders with .40S&SW firearms. Keep in mind that never fired brass used in factory.40S&W cartridges is almost perfectly safe (nothing is perfectly safe) when fired in all production .40S&W firearms.