This highly accurate .308 Caliber Windham Weaponry Flattop Upper Receiver Assembly features a Magpul MOE M-Lok Rifle Length Forend installed on its 20” Medium Profile Fluted Barrel. The Barrel is 4150M Chrome Moly Vanadium 11595E Steel, Chrome Lined in Bore and Chamber, rifled 1 turn in 10 inches – 6 lands & grooves – right hand twist. The muzzle is fitted with an A2 type .308 Flash Suppressor. A mounting stud for a Q.D. Sling Swivel is fitted to the Picatinny Rail Gas Block – which is on the same plane as the flat top type Upper Receiver’s MIL-STD 1913 Top Rail. The Upper Receiver is CNC machined from 7075T6 aircraft grade aluminum, hard coat black anodized to mil spec. Add your own .308 Bolt Carrier Assembly & Charging Handle to make this assembly complete.  This upper receiver assembly is compatible with Windham Weaponry .308 lower receivers only.