The Mossberg 510 Mini is the smallest pump shotgun in the Mossberg lineup, built for young children and very small-framed shooters. The 18.5-inch rifled barrel makes it a compact deer starter gun. Type: Pump Shotgun Action: Pump-Action Caliber: 20 Gauge Capacity: 3 Year introduced: 2011, USA Weight: 5 oz Overall length: 34.75" Status: Active Intended use: Deer Hunting, Youth Hunting, Slug Hunting