AR-10®A4 B-Series flat-top upper receiver made from forged 7075-T6 aluminum. Features a flat-top with MIL-STD 1913 rail. Thread size 1-7/16″x18″ UNEF-3A.
AR-10®A4 complete upper is our standard flat top upper with the standard port door rod used for all AR-10®’s that will utilize a 2-piece handguard. If a free float handguard is to be used, the 10002000 AR-10(T)™ complete upper is needed.