The 1911 handgun was originally designed to use the .45 ACP (Automatic Colt Pistol) caliber cartridge. It was intended to be a powerful and reliable sidearm for military and law enforcement use. The .45 ACP cartridge is known for its stopping power and has been used in a variety of firearms over the years.
However, the 1911 design has also been adapted to use other calibers over the years, including 9mm, 10mm, and .38 Super. Some 1911s are even chambered in more exotic calibers such as .22 LR or .357 SIG. It is important to check the caliber of your 1911 before purchasing ammunition to ensure that you are using the correct caliber for your firearm.