Rifles that accept multiple barrel assemblies. RMCS-3 accepts 5.56, 300 BLK and 7.62x39 uppers on one lower. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2016, USA Weight: 6.7 oz Overall length: 32.5" Status: Active Intended use: Range/Multi-Caliber