.45 Caliber cartridge. Sometimes used to refer to the firearms that fire such cartridges.
11.4mm in diameter, the average .45 caliber bullet weighs half an ounce.
Though there are many arcane .45 caliber cartridges, the two most common are the .45ACP (automatic Colt Pistol) and the .45 Colt, which is an obsolete but popular round. The .45 Colt round is longer than the .45ACP round, and was designed by Colt to fit their Single Action revolver, which the US Army used during the last decades of the nineteenth century. The .45ACP round was designed to be used in the 1911 pistol, by John Moses Browning. The gun was adopted by the US Army a few years after its creation, and was used by the United States until it was replaced by the Beretta M9 (Military designation for the Beretta 92) during the 1980s. Because it was used during both World Wars, Korea and Vietnam, hundreds of thousands of 1911s were produced. The Colt 1911 is often referred to as a “Colt .45” or “Government .45.” The pitfalls of the .45ACP cartridge are the large size of the bullet, heavy recoil and poor ballistics. Because the bullet is nearly 2.5 millimeters greater in diameter than the 9mm cartridge, far fewer can fit in a gun’s magazine, and the gun must be larger in order to accommodate the bullet. The heavy felt recoil is also a problem, because rapid or continued fire is difficult to maintain on target. The ballistics of the .45 caliber cartridge are also disappointing, the round travels nearly 200 feet per second slower than a 9x19 (9mm) cartridge. The 1911 pistol is still popular, despite being nearly 100 years old in design. The firearm’s single action mechanism and low magazine capacity have been overcome by some firearm manufacturers, most notably Para-Ordinance, whose LDA trigger systems are amazing, and whose high magazine capacity frames have revitalized the 1911 pistol.
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