I own one of those springer handguns. Granted I never really took it apart... the trigger rotates the barrel but does not cock the hammer. You have to do it by hand.
So... if it's built anything like the real thing, and I think the mechanical bits are close enough, you should get some good clues by looking at the schematics for a real Colt Python, or a S&W .357. How the cylinder turns is close to the same system. The 'piston' is in the grip.
Good luck with it.