The Mossberg 590A1 is the heavy-duty military version of the 590 series, featuring a thick-walled barrel, metal trigger group and safety, parkerized finish, and a heavy-duty forend. It is the primary pump shotgun used by U.S. military forces. Type: Shotgun Action: Pump-Action Caliber: 12 Gauge Capacity: 8 Year introduced: 1987, USA Weight: 8 oz Overall length: 39.5" Status: Active Military use: Yes Intended use: Military/Tactical