The 10mm Auto (10×25mm, official C.I.P. nomenclature: 10 mm Auto, official SAAMI nomenclature: 10mm Automatic) is a semi-automatic pistol cartridge first developed by Jeff Cooper and introduced in 1983 with the Bren Ten pistol.
Although it was selected for service by the Federal Bureau of Investigation in 1989 from the aftermath of the 1986 FBI Miami shootout, the cartridge was later decommissioned (except by the Hostage Rescue Team and Special Weapons and Tactics Teams) after their Firearms Training Unit eventually concluded that its recoil was excessive in terms of training for average agents' and police officers' competency of use and qualification, and that the pistols chambered for the cartridge were too large for some small-handed individuals. These issues led to the creation and following replacement to a shorter version of the 10mm that exists today as the .40 S&W. The 10mm never attained the mainstream success of this compact variant, but there is still an enthusiastic group of supporters who often refer to the .40 S&W as the ".40 Short & Weak" or "Short and Wimpy". The cartridge was originally known as the .40 Super.