The .45 ACP (11.43x23mm) (Automatic Colt Pistol), also known as the .45 Auto by C.I.P., is a cartridge designed by John Browning in 1904, for use in his prototype Colt semi-automatic .45 pistol and eventually the M1911 pistol adopted by the United States Army in 1911.
Ammo 45acp case box 375

.45 ACP Ammo

The .45 ACP has a good reputation for performance. The more energetic loads in the cartridge have the potential for remote wounding effects known as hydrostatic shock, but most attribute the effectiveness of the cartridge to large diameter bullets and reliable penetration.