yes understand, its a very short chamber shooting a paper cartridge - copy of the Dreyse Lady's rifle

look here http://forums.nitroexpress.com/showflat....true#Post275004

and you are right some airgun have such a rotating chamber to bring the bullet into the barrel. the early airgun history is not yet writen but one of the Dreyse airguns had exactly this rotating chamber taken from the older needle fire Lady's rifle to load the round ball.

could be this element came over this step into airgun design.