Standard Manufacturing Company DP-12, Pump, 12Gauge, 3" Chamber, 18.875" Double Barrel, 14Rd, DP-12. The first of its kind, Standard Manufacturings DP-12 is a premium self-defense, double-barreled, pump-action, 12-gauge shotgun that quickly fires 16 rounds when fully loaded. The one-of-a-kind shotgun not only sports two magazine tubes but two barrels as well! The pump-action DP-12 produces extreme firepower and consistent reliability.