SHOTGUN: BLACKWATER FIREARMS MODEL SENTRY 12, SERIAL NUMBER X20202340, BLUE / CCH, CASE NOT INCLUDED, SEMI - AUTOMATIC, 12 GAUGE, 18.5" Notes: BLACKWATER FIREARMS SENTRY 12 .The Blackwater Firearms Sentry 12 is a modern, AR-style 12-gauge pump-action shotgun that was introduced around 2020. It was designed by Iron Horse Firearms and initially marketed under the Blackwater Firearms name. The Blackwater/Iron Horse partnership later ended, so newer examples are generally associated with the Iron Horse Sentry 12. Key characteristics Action: Manual pump-action Gauge: 12 gauge Ammunition: 2 3/4-inch and 3-inch shells Barrel: 18.5-inch smoothbore, nitride-finished Magazine: Detachable 5-round box magazine; the original package included two magazines Weight: About 6.5 lb unloaded Overall length: About 36 inches Receiver: Lightweight aluminum upper with a polymer lower Controls: Ambidextrous controls modeled after the AR-15 layout Top rail: Approximately 17 inches of Picatinny rail for optics/accessories Stock: Fixed polymer stock with a relatively short length of pull