The AR103GN’s are Armalite’s flagship competition rifles that are built to win. This upper is light and ultra-fast. The low profile handguard covers a free-floating 13.5-in. barrel with Armalite’s own tunable muzzle brake that is pinned and welded to create an overall length of 16? – meaning this upper is not subject to NFA requirements! An adjustable gas block also allows the rifle to be individually set for optimal performance with a wide variety of ammunition. Includes a bolt carrier group and charging handle. Compatible with Armalite AR-10 B-Series lowers. Armalite AR 10 (B) 3 Gun Upper Assy 13.5" bbl