Features:Built on the versatile Bushmaster modular MSR upper platformBarreled upper receivers can be used on existing MSR-type lower receiversBushmaster 4150 chrome moly vanadium steel barrels feature hard-chrome lining in both bore and chamber for extended barrel lifeAll receivers feature integral brass deflectors and hard anodized finishEach assembly is factory headspaced, proofed, test fired and ready to use16 inches M4 barrel chrome-lined in both bore and chamberMilled low profile gas blockBolt carrier assembly
