Brownells has had huge success with the modernization of the AR-180 with its BRN-180 series of upper receivers. The BRN-180 uses a short-stroke piston system and will fit any standard AR-15 lower. The upper receivers are chambered in .223 Wylde and .300 Blackout respectively. Brownells is proud to introduce the new BRN-180SH chambered in .300 Blk and optimized for use with suppressors.