The AR-15 Assembled Upper Receiver comes with the port door already installed. This specific model does not have forward assist provisions. Forged from 7075-T6 aluminum, this assembled upper is precision machined to mil-spec M16/M4 specifications and features M4 feedramps. NOTE: Requires forward assist, charging handle, barrel, handguard, gas block, muzzle device, gas tube and BCG (Bolt Carrier Group) to complete.