The .10mm Auto Ammo is a powerful semi-automatic cartridge for pistols designed and introduced to the markets in 1983. Although being selected by the FBI in 1989, it was decommissioned because of the heavy recoil, which made the cartridge unsuitable for training average agents and police officers. Also, the chamber of the pistols for the .10mm Auto Ammo was too large for individuals with small hands. A former cartridge design was powered up, which resulted in a very powerful bullet that can retain a flat trajectory and high energy of a magnum cartridge for revolvers in a short, versatile rimless bullet for a semi-automatic pistol. The .10mm Auto Ammo produces a slightly higher energy level than the .357 Magnum Ammo at the maximum potential. The overall length of the .10mm Auto Ammo is 32mm, and the bullet diameter is 10.17mm. The 155-grain bullet variant of the .10mm Auto Ammo can travel at a velocity of 1,500 feet per second and creates an energy level of 775 ft.lbf.
The .10mm Auto Ammo was first designed and developed by United States Marine Jeff Cooper in 1983.
The .10mm Auto Ammo has three main uses. Hunting, defense, and tactical purposes. This cartridge is widely used for white-tailed deer hunting. The FBI and many law enforcement in the US still use the .10mm Auto Ammo for their operations.