the is the cocking handle pulled back, with the bolt retainer on.
this is my gun. it is a cross between a shotgun, an m16, and an ak47.
the gun holds 10 bullets in each clip (i made 2), is single shot, and fires about 6 and 1/2 metres from the end of the barrel, at my shoulder height (about 140cm), with the gun level.
the mechanism works in a basic way.
the bullets are inserted into the clip, stud to stud, bottom to bottom. the clip is attached into the reciever in the gun.
when you pull the cocking lever back (see pic 2), an axle stopper piece is pulled bak from out the barrel, past the camber, and up into a little rachet setup. the axle stopper is also attached to 2 rubber bands that run back down the barrel to where they are attached to part of the fore-sight.
at the same time, the bolt pushes a bullet out of the clip (if it is inserted), then up into the chamber, where it is held in place by a piece on a spring that pushes it up and squishes it against the roof of the chamber.
when you pull the trigger, the rachet setup i talked about earlier is released, allowing the axle stopper to slide towards the chamber at huge speeds. when it hits the bullet, it has to take it with it, as the barrel is not tall enough for it to pass. the bullet and the "hammer" then rush along the barrel, with the bullet leaving very, very fast at the other end.