The M-15A4BA2 Complete Upper Assembly features a double lapped, chrome lined barrel\Chrome Moly Vanadium. The Picatinny Rail on the upper receiver allow rapid and repeatable interchange of removable iron or scope sights, complete with A2 front sight.
Each ArmaLite Complete Upper Assembly includes a forged upper receiver assembly, barrel assembly, bolt carrier group and charging handle assembly. All complete upper assemblies are test fired as complete rifles before shipping.
M-15 Uppers use 7075-T6 Aluminum.
.750 at the journal (under the gas block)