The M4E1 upper receiver is a one-piece design combining the handguard mounting platform with the upper itself. It is machined from 7075-T6 aluminum with, M4 feedramps, .250 takedown pin holes, and supports barrels with a diameter up to 1". Included is a barrel nut and wrench, port door, and forward assist. NOTE: This upper is not piston-kit compatible. Requires charging handle, barrel, handguard, gas block, muzzle device, gas tube and BCG (Bolt Carrier Group) to complete.
Specifications:

Type	Complete Gas Impingement
Caliber	223 Remington/5.56 NATO
Sights	None, Optic Ready
Barrel Length
Barrel Material
Twist
Barrel Description
Barrel Finish
Receiver Description	7075-T6 Aluminum
Receiver Finish	Black Hard Coat Anodized
Handguards	Free-Floating
Handguard Finish	Black Hard Coat Anodized
Barrel Length Range