Our 7.5 inch, .223 caliber SAOD Pistol Upper Receiver features a Stainless Steel barrel with standard rifling with an 1/7 inch twist, and a .935 diameter Gas Block. SAOD Pistol or SBR uppers are assembled from parts that meet and exceed Mil-Spec or higher quality standards. Our pistol uppers are built on T-Marked M-4 receivers that are dry film lubed internally. Bolt carriers are properly staked and bolts are manufactured from Carpenter-158 or 9310 depending on the caliber. Uppers come with 4 rails on a free-float hand-guard along with a railed gas block. The barrels come with proper M-4 barrel extensions and are supplied by Lothar Walther who utilizes specialized engineered materials which yield greater accuracy and durability. Barrels are processed using the latest CNC technology available in all aspects of manufacturing and are CNC triple taper lapped.