The PWS MK116 is a 16-inch long-stroke piston AR-15 from Primary Weapons Systems of Boise, Idaho. The long-stroke piston system eliminates hot gas venting into the receiver, running cooler and requiring less frequent cleaning than direct-impingement ARs. The MK116 ships with a PWS FSC556 muzzle device that simultaneously functions as a flash suppressor and compensator. Used by some law enforcement agencies as a patrol rifle. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2010, USA Weight: 72 oz Overall length: 34.5" Status: Active Military use: Yes Intended use: Patrol Rifle, Duty Use, Home Defense