Well, I said I'd get back to you in 9 hours, looks like it could be 9.5. It took longer to make the diagram than I thought it would. Anyway...
<img src="
http://img.photobucket.com/albums/v611/car2/ROFASGM.png" alt="Image hosted by Photobucket.com">
(not to scale, and probibly not the best way to do things.)
Basicaly, when you fire:
The chamber is launched backwards. (recoil)
The chamber moving backwards uncovers the breach-loading hole in the barrel, and the ammo (being stored in a spring-loaded clip) is pushed in. At the same time, the piston on the "Venter" is pushed backwards, sucking in fresh air.
The chamber continues backwards, and seals on the venter.
The movment of the piston activates the release mechanism (look closely to find out how it works). At roughly the same time, the propane injector is activated.
With the piston released, it pushes clean air into the chamber, taking the propane along with it. The old air is expelled through some holes behind the breach-loading point.
The chamber is pulled back into position with a spring (not shown). When in position, it depresses a momentary that is wired in series with the trigger.
I'm expecting a cyclic rate of 1-2 rounds/sec, based on some breif calculations. This is mostly related to the mass of the chamber.
It works a bit like a 2-cycle engein... and shares some of it's problems; mainly that you arn't burning compleatly fresh air each time. This will yeild lower and somewhat inconsistent muzzle velocities.
Another idea: a recycled chamber revolver.
You have a few chambers. One of these is at the top, in ready to fire position. The rest of them are below, being vented by a few fans aranged in a semi-circle (or, each has a seperate, internal fan) , or being filled with propane. It works a bit like a cartrige fed, but the cartriges are constantly being reloaded.
A recoil-operated indexer is used to bring the next cartrige into position.
