.32 ACP also known as .32 Automatic Is a centerfire pistol cartridge. It is a semi-rimmed, straight-walled cartridge developed by firearms designer John Browning, initially for use in the FN M1900 semi-automatic pistol. It was introduced in 1899 by Fabrique Nationale, and is also known as the 7.65×17mmSR Browning or 7.65 mm Browning Short
John Browning engineered a number of modern semi-automatic pistol mechanisms and cartridges. As his first pistol cartridge, the .32 Automatic colt pistol needed a straight wall for reliable blowback operation as well as a small rim for reliable feeding from a box magazine. The cartridge headspaces on the rim.The cartridge was a success and was adopted by dozens of countries and many governmental agencies.
When the .32 Automatic colt pistol cartridge was introduced, it was immediately popular and was available in several blowback automatic pistols of the day, including the Colt Model 1903 Pocket Hammerless, the Savage Model 1907 automatic pistol, the Ruby pistol and the Browning Model 1910 automatic pistol. The popularity of the .32 Automatic colt pistol in the early half of the 20th century cannot be overstated—especially in Europe. Firearms expert Geoffrey Boothroyd, of the UK, informed author Ian Fleming, his countryman, that James Bond’s sidearm should be a Walther PPK chambered in .32 Automatic colt pistol . A significant factor in recommending this round was its availability throughout the world in the 1950s.
The .32 Automatic colt pistol has been chambered in more handguns than any other cartridge. Between 1899 and 1909, Fabrique Nationale produced 500,000 guns chambered for .32 Automatic colt pistol
.32 ACP was intended for blowback semi-automatic pistols, which lack breech locking mechanisms. It was John Pedersen with the Remington Model 51 that delivered a true locked breech for the .32 ACP cartridge. The low power and light bullet of the cartridge allowed Browning to incorporate a practical blowback mechanism in a small pocket-size pistol. It is still used today, primarily in compact, inexpensive pistols, unless the pistol is used for ISSF competition, where the cost then escalates. Cartridges in .32 ACP are also sometimes used in caliber conversion sleeves, also known as supplemental chambers, for providing an alternative pistol caliber carbine function in .30-caliber hunting and service rifles.
Some comparison of the .32 Automatic as defined by SAAMI and the 7.65 Browning as defined by CIP may be useful. Although some of the cartridge measurements differ by as much as 0.16 mm, the names are considered to be synonymous. However, the maximum average pressure – as measured by a transducer on the test barrel – is 20,500 psi (1,410 bar) according to SAAMI, while CIP allows up to 1,600 bar (23,000 psi). This may explain why the cartridges from European manufacturers tend to chronograph at higher muzzle velocities than those from American manufacturers.