The Radical Firearms AR-15 upper receiver assembly comes ready out of the box to attach to any Mil-Spec lower receiver. It has a forged M4 railed upper so you can easily attach scopes and red dot sights to the MIL-STD rail. The upper receiver is does not include bolt carrier group or charging handle but comes complete with a Mil-Spec upper parts kit that includes an ejection port cover and forward assist. The barrel is 16” of 4140 chromoly steel with a Melonite coating and is attached via a steel barrel nut.