• This cartridge was developed by John Browning and was adopted by the United States Ordnance Department along with the Colt-Browning automatic pistol in 1911. It has also been made the official military handgun chambering by several other governments, notably Argentina, Mexico and Norway. The 45 Automatic is the most powerful military handgun cartridge in use today. This is a heavy and powerful sub-sonic round. Although its muzzle energy can exceed 400 ft-lbs, its velocity and bullet weight creates a steep trajectory curve that limits its effective range to self-defense distances.