.25 ACP
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The .25 ACP, also known as the .25 Auto, .25 Automatic, or 6.35×16mmSR is a semi-rimmed, straight-walled centerfire pistol cartridge introduced by John Browning in 1905 alongside the Fabrique Nationale M1905 pistol. Wikipedia
Bullet diameter: .2512 in (6.38 mm)
Designed: 1905
Maximum CUP: 25,000 CUP
Maximum pressure: 25,000 psi (170 MPa)
Place of origin: United States and Belgium
Produced: 1905–present
Rifling twist: 1:16