Automatic Colt Pistol

The addition Automatic Colt Pistol , or ACP for short , describes some pistol calibres .

They were all developed in the early 20th century by John Moses Browning , who designed new pistol models for the two manufacturers Colt and Fabrique Nationale (FN) . At the time, there were only a few established calibers for self-loading pistols, so Browning pioneered both fields. All calibers of the ACP series have in common that the cartridge cases are straight-walled, while many other pistol calibers of the era used bottle-shaped cases .

In 1900 the FN Browning Model 1900 pistol in .32 ACP caliber was introduced in Europe and the Colt Model 1900 in .38 ACP caliber in America . However, the latter was quickly perceived as too weak in the following years and has been considered obsolete since the introduction of an increased variant under the designation .38 Super in 1929. The other calibres of the ACP series followed between 1900 and 1908. They were not only used in pistols from Colt and FN, but quickly gained great popularity worldwide. .32 ACP was at times considered to be the caliber in which more handguns were produced than any other caliber. The Colt M1911 pistol in caliber .45 ACP has been in use by the US armed forces since 1911 and helped make the strongest member of the ACP range one of the most widely used calibers for military pistols and submachine guns .

Alternative names for the calibers of the ACP series often use the terms “ Browning ”, “ Auto ” or “ Colt ”, although by no means all calibers with similar names belong to the ACP series. The 9 mm Browning Long pistol caliber, also developed by Browning in 1903 , was never called ACP.

The number indicates the approximate diameter of the projectile or cartridge in inches. As usual in the English-speaking world, the 0 in front of the decimal separator, which is the point in English, is omitted. For example, caliber .25 ACP has a projectile diameter of 0.251 ", which corresponds to 6.4 mm.

ACP series caliber

caliber	Designation according to CIP	Designation according to SAAMI	further names
.25 ACP	6.35 Browning	25 automatic	6.35 × 15.5 mm rear 6.35 × 16mm SR
.32 ACP	7.65 Browning	32 automatic	7.65 × 17 mm rear
.38 ACP	no homologation	38 automatic	.38 Auto
.380 ACP	9 mm Browning court	380 automatic	9 mm short 9 × 17 mm. 380 Auto
.45 ACP	45 car	45 automatic

Remarks

1. ^ W. Todd Woodard, Shooter's Bible Guide to Cartridges, New York 2011.