The Radical Firearms FCR Upper Receiver is a flat top, law-enforcement grade, drop-in receiver, ready to be mounted to any Mil-Spec AR-15 lower. This fully MIL-STD receiver provides a high-quality upper for any level budget or shooter. It comes complete and assembled with upper receiver, forward assist, ejection port door, barrel nut. 16" barrel and an A2 flash hider. This 300 Blackout model has a black nitride barrel with black hardcoat anodized receiver and handguard.