Core 15 MOE Scout AR-15 Complete Upper Assembly,with OD Green handguard, in .223 Rem/ 5.56 NATO 1:9 twist. The Core 15 MOE Scout M4 16″ upper receiver represents the result of Core rifle systems attention to detail and quality parts to provide you with the best value to performance ration on the market. This particular complete upper assembly is forged from 7075-T6 aluminum that is type III class II hard coat anodized finished with M4 feed ramps. The upper receiver a flat top type with a built in 1913 picatinny rail complete with laser engraved T markings. The bolt assembly is magnetic particle inspected to ensure quality and they bolt carrier and key are also chrome lined stainless steel.