.25 ACP

.25 ACP
.25 ACP cartridge with scale
Type	Pistol
Place of origin	United States and Belgium
Production history
Designer	John Browning
Designed	1905
Produced	1905–present
Specifications
Case type	Semi-rimmed, straight
Bullet diameter	.2512 in (6.38 mm)
Land diameter	.2429 in (6.17 mm)
Neck diameter	.276 in (7.0 mm)
Base diameter	.278 in (7.1 mm)
Rim diameter	.302 in (7.7 mm)
Rim thickness	.043 in (1.1 mm)
Case length	.615 in (15.6 mm)
Overall length	.910 in (23.1 mm)
Rifling twist	1:16
Primer type	Small pistol
Maximum pressure	25,000 psi (170 MPa)
Maximum CUP	25,000[1] CUP
Ballistic performance
Bullet mass/type Velocity Energy 22 gr (1 g) +P HP 1,750 ft/s (530 m/s) 150 ft⋅lbf (200 J) 35 gr (2 g) JHP 900 ft/s (270 m/s) 63 ft⋅lbf (85 J) 45 gr (3 g) JHP 815 ft/s (248 m/s) 66 ft⋅lbf (89 J) 50 gr (3 g) FMJ 760 ft/s (230 m/s) 65 ft⋅lbf (88 J) 60 gr (4 g) Lead 850 ft/s (260 m/s) 96 ft⋅lbf (130 J)
Test barrel length: 2" Source(s): Buffalo Bore[2] Ballistics 101[3]

The .25 ACP (Automatic Colt Pistol), 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.