The Mossberg 590A1 is the military-specification version of the 590 platform featuring a heavy-walled barrel, metal trigger group and safety components, and a parkerized finish meeting MIL-SPEC-3443 requirements. Type: Shotgun Action: Pump-Action Caliber: 12 Gauge Capacity: 9 Year introduced: 1987, USA Weight: 64 oz Overall length: 41" Status: production Military use: Yes Intended use: military,law-enforcement,tactical