CMMG's foundational AR-15 platform offered in numerous barrel lengths and calibers. The Mk4 series covers 5.56, .22 LR, 9mm, 5.7x28mm, and more. Type: Carbine Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2012, USA Weight: 112 oz Overall length: 32" Status: Active Intended use: Sport Shooting, Home Defense, Hunting