Heckler & Koch Mark 23 Country Germany Type Semi-automatic pistol Manufacturer Heckler & Koch Introduction 1991 Specifications Weight 1.21 kg (2.7 lb), empty 1.47 kg (3.2 lb), loaded 2.29 kg (5.0 lb), loaded, with suppressor and LAM Length 245 mm (9.5 in), without suppressor 421 mm (16.5 in), with suppressor Barrel length 149 mm (6 in) Cartridge .45 ACP (AA18, A475) Action Short recoil, DA/SA Rate of fire Semi-automatic Effective range 50 m Feed system 12-round detachable box magazine

The Heckler & Koch MK23 Mod 0 is a handgun consisting of a match grade semi-automatic pistol, a laser aiming module (LAM), and suppressor. It was adopted by the United States Special Operations Command (USSOCOM) for special operations units in the 1990s.

While the designation applies to the complete system, it also commonly used in reference to the pistol component itself. The pistol itself, chambered for the .45 ACP cartridge, was developed by Heckler & Koch, and was selected over the Colt OHWS through the USSOCOM Offensive Handgun Weapon System (OHWS) program. The initial LAM and suppressor were developed by Insight Technology and Knight\'s Armament Company (KAC), respectively.

The MK23 Mod 0 was built as an \"offensive\" handgun for U.S. special operations forces under USSOCOM, as per request made in 1989. Military versions of the weapon have the writing \"MK23 USSOCOM\" engraved on the slide.