The Primary Weapons Systems MK116 features PWS DI (Long-Stroke Gas Piston) operating system, providing a cleaner-running alternative to direct impingement in a high-quality AR-pattern rifle. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 2014, USA Weight: 7.5 oz Overall length: 35.5" Status: Active Intended use: Tactical, Home Defense, Precision