Armscor Meriva Pump Shotgun, 12 Gauge, 3 Chamber, 18.5 Barrel, Parkerized Finish, Black, Rifled Sight, 5 Rounds CR-103 The Rock Island Armory Meriva 12 Gauge Pump Action Shotgun features a black anodized finish, smooth bore 18.5" barrel, and 3" chamber. The Meriva also sports a 5 tube capacity and an overall length of 40.15".