Piston Design (ghetto sketch)

[Moonbogg]

OK, heres my idea for an inline piston hybrid. It uses pressure differential like a standard piston. The piston housing bolts to the end plate and the housing has ventilation holes, allowing combustion pressure to push the piston back, overcoming the pilot pressure caused from compressed air. Pretty friggin simple and consists of 3 parts. I like the idea because i would get a standard piston (tried and true) in an inline configuration, eliminating the need for T fittings. What do you think?
The sketch is slightly rough, but you might get the idea.

EDIT: I plan on keeping the active surface area of the piston as tiny as possible, allowing good pressure build up but with minimal pilot pressure. That way, when it opens, the pressure acting on the full face of the piston will very easily open it and as fast as possible.

[Technician1002]

It looks like one of the sketches I'm playing with. Make sure the piston structure does not interfear with the flow out the barrel when open. I was toying with one with the piston in the center of a 20 LB propane tank. 3 3 inch barrel would extend into the tank from one end and the piston cylinder would extend in from the other end. This would make the piston servicable.
Due to the size of the tank, and composition, it would most likely need to be a low mix.