When the lever (deep blue) moves a little, the inner ring (also deep blue) wil turn a little, to release the piston (purple) wich would otherwise be pushed by the inner ring on to the rubber O-ring (red). When the piston is released, it’ll be launched into the cylinder by the CO2 gas from the flask (lightblue). The cylinder will be pushed out by the gas and the force of a piston flying against the end of the cylinder.

Kinda like the bolt on your average semi-automatic rifle..

The lever system consists of an lever (blue) wich moves by a spring (lightgray, in the lever), when the trigger (red) releases the lever. The trigger is moved by an servo (your average servo.. in white) but the servo will unlock the kneejoint (purple) first before the trigger moves. The kneejoint is there to make it all more shockproof...I hope ^___^;;;