10mm Auto - History

History

The 10mm Auto cartridge was championed by famous firearms expert Colonel Jeff Cooper. It was designed to be a medium-velocity pistol cartridge with better external ballistics (i.e., flatter trajectory, greater range) than the .45 ACP and capable of greater stopping power than the 9×19mm Parabellum. When Norma designed the cartridge at the behest of Dornaus & Dixon Enterprises for their Bren Ten pistol (a newly developed handgun borrowing base design from the CZ 75), the company decided to increase the power over Cooper's original concept. The resulting cartridge—which was introduced in 1983 and produced since—is very powerful, packing the flat trajectory and high energy of a magnum revolver cartridge into a relatively short, versatile rimless cartridge for a semi-automatic pistol.

The cartridge has failed to attain the same level of popularity as the 9×19mm Parabellum, .45 ACP, and the .40 S&W cartridges. This may be explained by the fact that full-powered 10mm Auto loads generate significantly more recoil and muzzle blast compared to most other common handgun cartridges. Additionally, the ballistics of milder 10mm Auto loads can be duplicated in smaller guns using the less expensive .40 S&W cartridge.

The 10mm Auto earned a reputation for battering guns early on, largely because manufacturers attempted to simply rechamber a .45 ACP design for the 10mm Auto. The .45 ACP works at a much lower pressure and velocity, and the frame and slide designed to handle the .45 ACP cannot handle the greatly increased forces of a 10mm Auto without substantial strengthening. Later guns, such as the Glock 20, Glock 29, and the Smith & Wesson Model 1006, were built around the cartridge to help increase durability and reliability.

Another issue with early acceptance was the result of manufacturing problems with the Bren Ten. The contractor who was to manufacture the magazines were unable to deliver them on time and as such, many early Bren Tens were shipped to dealers and customers without magazines. The relatively high price of the Bren Ten compared to other pistols (manufacturer's suggested retail price in 1986 was U.S. $500) also contributed, and the company ceased operations in 1986 after only three years of manufacture. Had it not been for Colt making the rather surprising decision in 1987 to bring out their Delta Elite pistol—a 10mm Auto version of the Government Model—the cartridge might have sunk into obsolescence, becoming an obscure footnote in firearms history.

Thanks to media exposure (primarily in the television series Miami Vice), demand for the Bren Ten increased after production ceased. In the succeeding five years, prices on the standard model rose to in excess of U.S. $1,400, and original magazines were selling for over U.S. $150.

The F.B.I. briefly field-tested the 10mm Auto using a M1911-frame platform and a Thompson Model 1928 submachine gun before adopting the round in the late 1980s along with the Smith & Wesson Model 1076, a short barreled version of the Model 1026 with a frame-mounted decocker. During the testing of the new service caliber, it was concluded that the full power load of the cartridge would result in undesirable recoil. Subsequently, a requirement for reduced-recoil loading was then submitted. This later became known as the "10mm Lite", or "10mm F.B.I." load. Pistol reliability problems increased with this lighter load and Smith & Wesson saw this as an invitation to create something new: a shortened version of the 10mm case. This improved cartridge was named the .40 Smith & Wesson. The shorter case length allowed function in a 9mm sized pistol; the advantage being that smaller-handed shooters could now have smaller frame sidearms with near 10mm performance. Colloquially called the "Forty", this innovation has since become a common handgun cartridge among law enforcement agencies in the U.S., while the popularity of the parent 10mm Auto has diminished. Colt, Dan Wesson Firearms, Glock, Kimber Manufacturing, Nighthawk Custom, Smith & Wesson, STI International and Tanfoglio are some of the few manufacturers that still offer handguns in 10mm Auto.

The 10mm outperforms the .40 S&W by 200–250 ft/s (61–76 m/s) for similar bullet weights when using available full power loads, as opposed to the "10mm F.B.I." level loads still found in some ammunition catalogs. This is due to the 10mm Auto's higher S.A.A.M.I. pressure rating of 37,500 psi (259,000 kPa), as opposed to 35,000 psi (240,000 kPa) for the .40 S&W, and the larger case capacity, which allows the use of heavier bullets and more smokeless powder.