In the early-1990s U.S. Special Operations Command (USSOCOM) opened the Offensive Handgun Weapon System (OHWS) program. Heckler & Koch took on the challenge of building a .45 ACP handgun, designed to fire +P ammunition, with a silencer and laser/light module. Heckler & Koch eventually won the contract and delivered the HK SOCOM (Mark 23). The Mark 23 uses either 10 or 12 round steel factory magazines that are double stack. These magazines are extremely well made, they are treated with Heckler & Koch's 'hostile environment' finish. If you own a Mark 23, it's essential to own additional magazines for this impressive weapon system.