10mm Ammunition

The 10mm Auto is the parent cartridge to the 40 S&W. Adopted by the FBI, the 10mm, running 170 grain over-pressured Norma loads, was abusive to guns and difficult for smaller agents to control. When loaded to it's full potential,

From Wikipedia:

Although it was selected by the Federal Bureau of Investigation in 1989 for field use from the aftermath of the 1986 F.B.I. Miami Shootout, the cartridge was phased out after their Firearms Training Unit eventually "concluded that its recoil was excessive in terms of training for average agent/police officer competency of use and qualification",^[6] and that the pistols that chambered it were too large for some small-handed individuals. These issues led to the creation and following adoption of a shorter version of the 10mm that exists today as the .40 Smith & Wesson. 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".