The Heckler & Koch MK 23, MK 23 MOD 0, Mark 23, or USSOCOM MARK 23 is a semi-automatic large-frame pistol chambered in .45 ACP, designed specifically to be an offensive pistol. The USSOCOM version of the MK23 came paired with a laser aiming module (LAM) and suppressor. The USSOCOM MK23 was adopted by the United States Special Operations Command (USSOCOM) for special operations units, beating out the nearest competitor, Colt's OHWS. Development of the pistol began in 1991 as special operations representatives identified the need for an "Offensive Handgun Weapons System—Special Operations Peculiar", and delivery of the pistols began in May 1996 to the special operation units.