Centerfire pistol cartridges using .400-.401-inch (10 mm) bullets. This catalog covers 40 S&W and 10mm Auto – the two mainstream semi-auto calibers that share bullet diameter but differ significantly in power, case length, and intended role.
Cartridges in this catalog:
40 S&W
40 S&W is a shortened, reduced-pressure version of the 10mm Auto, designed to fit standard 9mm-frame pistols. It became the dominant law enforcement cartridge in the US through the 1990s and 2000s, offering more energy than 9mm with manageable recoil. It remains a strong choice for handloaders who want a step up from 9mm without the full snap of 10mm Auto.
10mm Auto
10mm Auto is the full-power original. It drives .400-inch bullets significantly faster than 40 S&W, pushing into territory that overlaps with light 41 Magnum loads. It is a serious hunting and field defense cartridge for large, dangerous game at handgun ranges, and has seen renewed popularity among handloaders who want maximum semi-auto pistol performance. Dedicated 10mm frames are required – the cartridge is too long and too powerful for standard 9mm-frame pistols.