I'm not really sure with this one but i guessyou might need to do some research first. I opened up mine and found outthat when you cock it ( the old airsoft guns that you have to cockbefore firing ) it compresses a spring and locks it in place using thetrigger sear which has a small spring that compresses when u pull thetrigger. pulling the trigger unlocks the sear from the cap at the end ofthe spring. spring goes forward in an instant, cap moves forwardbuilding up air pressure until there's enough pressure to blast thepellet down the barrel and out to the target. btw, the cap's greased toallow the cap to move. I hope you get what I'm saying, I'll just posta picture so you'll understand.