The M590 12ga is a shotgun mainly used by guard backups.
- "Intended for use in harsh conditions, such as combat or hunting waterfowl, the M590 pump-action shotgun in both effective, and easy to maintain."
Based upon the real-world Mossberg 590 12-Gauge Combat Shotgun, the pump-action is fitted with an 8-round capacity and is obtained from various locations in the Terminus Hotel, a dead security guard in the Rosewood Orphanage, and in several other missions in the game, including the mission in which Kane & Lynch make a cameo.
- Rosewood: On the ground near the dead security guard in the chapel; carried by one of the henchmen near the exit.
- Birdie's Gift: Carried by Lynch.
- Shaving Lenny: Upstairs of Tyler Colvin's store.
- End of the Road: Laying on the ground next to the trunk of the car.
- Skurky's Law: In the evidence room inside the courtroom.
- Worn M590 12ga: Worn down, dirty, scuffed. A less reliable variant.
- Police M590 12ga: A clean, advanced version commonly found in use by the police. This version can be used in Contracts mode.