How do you insert a CO2 cartridge into a Powerline 1200 pistol?

Take the left plastic grip off the gun. It should pop off. Remove the old C02 bottle (You may have to unscrew the bottom screw a little. ) Replace the C02 with a new 12 gram C02 bottle. Then using a coin screw the bottom screw in until it stops. This will charge the gun with new C02.