There was a time when the shotgun was the primary long gun for police, but in many departments, it has been relegated to a secondary, or even less-lethal weapon, as it has been replaced by the patrol rifle or carbine. 

We’ve previously discussed how new ammunition developments have made the shotgun more valuable than ever as a lethal tool, but regardless of whether yours is reserved for launching buckshot or beanbags, you need to keep it clean and ready for service.

While semiautomatic shotguns like the Benelli M-series guns, the Beretta 1301, or FN SLP have become more popular in recent years, the traditional choice for police use has always been a pump-action gun. Today, we’ll look at how to disassemble one of the most popular guns in this class, the Mossberg 500/590-series.

STEPS TO DISASSEMBLE THE MOSSBERG 500/590 SERIES SHOTGUN

1. The first step in disassembly is to ensure your shotgun is unloaded. To accomplish this, point and keep the barrel in a safe direction while accomplishing the following:

a. Place the safety to the “ON” (aft) position.

b. Push the button behind the trigger guard to unlock the action, and slowly pull the forearm all the way to the rear. This will eject a shotshell that is in the chamber. Working the action slowly will allow you to safely capture the ejected shotshell.

c. If there was another shotshell in the magazine, it will now be on the elevator. Roll the gun onto its right side, to allow this shotshell to fall out of the ejection port, into your hand.

d. Physically and visually check the chamber and elevator to ensure there are no shotshells present, then move the forearm forward and close the action.

e. Reach into the loading port underneath the gun, and push on the cartridge stop in the left sidewall of the gun with your right thumb. This will allow the base of the first shotshell to partially exit the magazine tube. Using slight thumb pressure on the base of the shotshell to help it clear the elevator, pull it free from the magazine and out the loading port on the bottom of the gun.  Repeat this process until all shotshells have been removed from the magazine.

f. Once all shotshells have been removed, physically and visually check the magazine tube to ensure there is no ammunition left in the magazine.

2. Move the forearm to a middle position where the action is halfway open.

3. Unscrew the takedown screw (or magazine cap, on some models) on the end of the magazine tube, to release the barrel.

4. Pull the barrel forward, off the gun.

5. With a non-marring tool, push the trigger group pin out of the gun from the right side.

6. Remove the trigger group from the action by pulling the rear of the trigger guard down and aft, simultaneously.

7. Remove the cartridge interceptor from the right sidewall of the gun.

8. Remove the cartridge stop from the left sidewall of the gun.

9. After ensuring it’s lined up with the relief cuts in the receiver, pull the bolt slide out the bottom of the receiver.

10. Remove the forearm from the gun by pulling it forward, off the receiver.

11. Remove the bolt by pushing it forward, out the front of the receiver.

12. Remove the elevator, by pinching the arms together so that their studs clear the holes in the sides of the receiver, then lifting it out.

13. (If desired) Remove the screw that holds the ejector in place on the left sidewall, and remove the ejector.

14. (If desired) Unscrew the magazine tube from the receiver, being careful as you near the end because it will be under slight spring pressure.  Remove the spring and follower from the magazine tube.

Now that you have your shotgun disassembled, you can properly clean and inspect it, to ensure it will give you reliable service in the field.