The Mossberg 500 ATI is the tactical variant with an ATI-style stock, pistol grip, 18.5-inch cylinder-bore barrel, and heat shield. Dual extractors and ambidextrous tang safety. One of the most reliable pump shotguns at any price. Type: Pump Shotgun Action: Pump-Action Caliber: 12 Gauge Capacity: 5 Year introduced: 1961, USA Weight: 5.5 oz Overall length: 28" Status: Active Intended use: Home Defense, Tactical, Law Enforcement