.380 ACP

The .380 ACP (Automatic Colt Pistol) pistol cartridge is a rimless, straight-walled pistol cartridge developed by firearms designer John Browning. The cartridge headspaces on the mouth of the case. It was introduced in 1908 by Colt, and has been a popular self-defense cartridge ever since. Other names for .380 ACP include .380 Auto, 9mm Browning, 9mm Corto, 9mm Kurz, 9mm Short, 9×17mm and 9 mm Browning corto (which is the CIP designation). It is not to be confused with .38 ACP, 9mm Makarov or 9mm Luger.

Design
The .380 ACP cartridge was designed for early blowback pistols which lacked a barrel locking mechanism. The locking mechanism that is found on most other pistols is not necessary for the .380 because of the round's relatively weak bolt thrust when fired. The recoil spring and the mass of the slide are enough to buffer the recoil energy of the round. This simplifies manufacture of pistols chambered for such a round, generally thereby lowering the cost. It also permits the barrel to be permanently fixed to the frame, which promotes accuracy. There have, however, been a number of locked-breech pistols chambered in .380 ACP. There have also been some diminutive submachine guns, such as the Ingram MAC-11 and vz. 83.

Uses
The .380 ACP has experienced widespread use in the years since its introduction. It was famously used by many German officers during World War II in the Walther PPK, as well as by Italian forces in the Beretta M1934. However, as a service pistol round, its power did not provide suitable penetration for combat. It did find use as a backup gun due to low recoil, and is popular in the civilian market as a personal defense round. The .380 ACP round is considered suitable for self-defense situations, and as a result, it has been a viable choice for concealed carry pistols. The combination of decent penetration in close range defense situations with light recoil has made it a viable round for those who wish to carry a small, lightweight handgun that can still provide adequate defense. It was the round used in Defense Distributed's "Wiki Weapon" project to successfully 3D print a firearm.

Performance
The .380 ACP is compact and light, but has a relatively short range and less stopping power than other modern pistol cartridges. According to gun author Massad Ayoob, "Some experts will say it's barely adequate, and others will say it's barely inadequate." Even so, it remains a popular self-defense cartridge for shooters who want a lightweight pistol with manageable recoil. It is slightly less powerful than a standard-pressure .38 Special and uses 9 mm (.355 in) diameter bullets. The heaviest bullet that can be safely loaded into the .380 ACP is 115 gr, though the standard has long been 85, 90 or 95 grains (5.5, 5.8 or 6.2 g). The .380 has had something of a recent upsurge in popularity with the increase of concealed carry laws, as have the compact and inexpensive pistols that make use of it. Popular pistols chambered in .380 ACP include the Colt Mustang pocketlite, Llama Firearms Micromax, SIG Sauer P238, Beretta .380, Walther PPK/S, Walther PK380, Bersa Thunder 380, CZ 83, SIG Sauer P230/P232, Kel-Tec P-3AT, Smith & Wesson Bodyguard 380, Diamondback DB380, Kahr P380, Ruger LCP and Taurus TCP 738. Glock also produces models in .380, though they are not available to the U.S. market because they do not earn enough "points" for importation under Federal law.

The wounding potential of bullets is often characterized in terms of a bullet's expanded diameter, penetration depth, and energy. Bullet energy for .380 ACP loads varies from roughly 190 to 220 ftlbf. The table below shows common performance parameters for several .380 ACP loads. Bullet weights ranging from 85 to 95 gr are common. Penetration depths from 6.5 to 17 in are available for various applications and risk assessments.

Key:
 * Expansion – expanded bullet diameter (ballistic gelatin).
 * Penetration – penetration depth (ballistic gelatin).
 * PC – permanent cavity volume (ballistic gelatin, FBI method).
 * TSC – temporary stretch cavity volume (ballistic gelatin).

Synonyms

 * .380 Auto
 * 9mm Browning
 * 9mm Browning Short
 * 9mm Corto
 * 9mm Court
 * 9mm Kratak
 * Kratka 9 (Devetka)
 * 9mm Kurz
 * 9mm Scurt
 * 9mm Short
 * 9×17mm