The M5 .308 Assembled Upper Receiver comes with both the port door and forward assist hardware preinstalled. Forged from 7075-T6 aluminum, this assembled upper is precision machined to accept standard .308 components and is the perfect upper for your big bore build. Match this with our M5 .308 lower receiver for a solid and dependable fit. | Aero Precision M5 Threaded Assembled Upper Receiver