The MCX is SIG's modular rifle-format pistol chambered in 5.56x45mm, designed as a short-barreled alternative to the AR-15 platform with folding-stock capability and a multi-caliber design. A short-stroke gas piston system — borrowed from the MPX — provides reliable operation with the shorter barrel. The MCX was originally developed in response to a SOCOM requirement for a suppressed short-barreled weapon. Type: Semi-Auto Pistol Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 2015, USA Weight: 6.5 oz Overall length: 16" Status: Active Military use: Yes Intended use: military, tactical, competition, home_defense