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The 380 ACP was developed by John Browning. 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.
The 380 ACP is a popular pistol round chambered for semi-automatic handguns and small submachine guns using direct-blowback and short-recoil mechanisms. The round is a straight-walled cartridge with a relatively lower peak chamber pressure than more modern sporting, military or defensive rounds. The 380 ACP works very well with direct blowback handguns. There are no known carbines or rifles that use the 380 ACP.
The 380 ACP is a popular self defense round used in many nations. The 380 ACP is often used in nations where civilians are prohibited from owning firearms capable of using military ammunition.
While considered "weak" compared to more potent rounds such as the .45 ACP, the 9mm Parabellum (9x19mm), any of the magnum handgun rounds, the 10mm Norma, the .40 S&W or its closest relative, the 9mm Makarov, the 380 ACP is an effective self defense round if shot placement is taken carefully. Handguns using the 380 ACP are often very easily concealed, have minor muzzle blast and can be more easily used with suppressors than most of the more powerful combat and sporting rounds used in handguns today.
The 380 ACP is not used in formal target shooting competition though civilians and agencies may use the round for qualification and recreational target shooting.
The 380 ACP is available from both military and commercial sources. Frangible, hollow point, and Full Metal Jacket versions are readily available. Typical bullet weights range from 70 grains (approximately 4.5 grams) to 110 grains (approximately 7 grams).
In spite of its close relation to the 9mm Makarov round the 380 ACP and 9mm Makarov are not nominally interchangeable. The round cannot be safely used in a 9mm Parabellum firearm. The 9mm Parabellum round will not chamber into a 380 ACP firearm.