This is the M4 barreled upper assembly patterned after our unique “SRC” rifle. Its tack-driving 16” M4 profile barrel is chrome lined and machined from 4150 Chrome Moly Vanadium steel. It is rifled with a 1 x 7” right hand twist and includes an A2 flash suppressor. A 1913 Mil Std rail gas block with sling swivel and bayonet lug allows the attachment of a variety of front sights. M4 dual heat shield handguards complete the barrel. The machined aluminum flat top upper receiver is assembled with the forward assist and ejection port cover.