Mossberg 590RM, Pump Action Shotgun, 12 Gauge, 2.75 Chamber, 18.5 Barrel, Matte Finish, Black, Collapsible Stock, Heat Shield, Top Picatinny Rail, Flip Up Backup Iron Sights, 1 Magazine, 10 Rounds 50213 The 590RM Rotary Safety Selector shotguns utilize the first production double-stack magazines made for pump-actions providing more efficient capacity vs. length than competitive designs. Plus, they combine time-tested Mossberg durability with ground-breaking features like a rotary safety selector; a compact, ergonomically-designed forend, and an integrated barrel/heat shield combination.