Repair A Co2 Cartridge Gun

Paintball guns rely on CO2 gas cartridges to activate the firing mechanism being used to expel paintball capsules from the barrel. Loose fittings inside a paintball gun will dilute the intensity of the burst of gas generated by the CO2 cartridge. To repair a paintball gun that is not firing at its full intensity, partially disassemble and replace the O-rings that seal the gun. The procedure is similar, with slight differences, for all paintball guns. A few common tools are needed, as are replacement O-rings acquired from a hobby store or a gun-supply shop.


1. Remove the cartridge clip from the bottom of the CO2 cartridge paintball gun’s handle. Place it aside. Cock the firing plate at the top of the gun towards the hammer and turn the gun upside down. Shake the gun to dislodge any stuck paintball capsules that might be in the firing chamber. Turn the gun right-side up and confirm there are no capsules in the chamber. Release the cocking plate. Squeeze the trigger to release the hammer that was pulled back when the cocking plate was engaged.

2. Place a sheet of newspaper on a table to protect the surface. Place the gun on the newspaper with the barrel facing to the left.

3. Remove the screws from the top edge of the gun, below the tip of the barrel and below the hammer, with a Phillips screwdriver. Remove the screw next to the trigger guard, if one is present, with the screwdriver.

4. Hold the gun so that the hammer is facing you. Remove the screw from the top edge of the gun, in front of the hammer with the screwdriver. If there is no screw, ignore this step.

5. Press the tip of the screwdriver against the locking pin that is on the right side of the gun, above the trigger guard. Grip the locking pin now that it is extruding from the hole in the left side of the gun with a needle-nose pliers. Pull the pin out of the gun and place it aside.

6. Slide the cocking plate towards the barrel of the gun and off the top. Place it aside. Place the gun on the newspaper with the barrel facing to the left. Remove any screws from the bottom left and right edges of the gun on the left side with the screwdriver. Pull the left plate off the gun.

7. Remove the screws from around the trigger-guard mechanism with a Phillips jeweler’s screwdriver. Pull the trigger guard mechanism off the gun and place it aside.

8. Blow out the gun with bursts of compressed air. Run a gun cleaning rod through the barrel to dislodge any loose dirt. Blow out the barrel with a burst of compressed air.

9. Grip the O-ring that is next to and below the tip of the barrel with the jaws of the pliers. Tweezers can be used if you are concerned about damaging the O-ring. Pull the O-ring off the gun. Dispose of the O-ring.

10. Remove the O-ring from the well where the trigger guard mechanism was removed. Dispose of this O-ring also. Remove any other O-rings that can be seen inside the gun and dispose of them.

11. Place appropriately sized replacement O-rings in the gun; reverse the removal process of the original O-rings in order to seat the replacements properly. Blow out the gun with bursts of compressed air.

12. Unscrew the CO2 cartridge from inside the cartridge clip. Pull the O-ring off the nipple in the clip with the jaws of the pliers. Insert an appropriately sized replacement O-ring inside the clip and around the nipple. Seat the replacement O-ring so that it occupies the same position as the original O-ring did. Screw the CO2 cartridge back into the nipple.

13. Reverse the disassembly process to put the gun back together. Insert the magazine clip back into the bottom of the gun. Wipe the gun off with a clean soft cloth.