air comressed spring piston

[sum_kid]

I just had an idea:
A spring piston design where the spring provides the energy (like a break barrel airgun). The difference bing that my design has compressed air behind the piston so it wouldn't need a really strong spring. Although it would need a strong trigger design.
I was making a diagram but messed up and got pissed off so yeah... any thoughts?

[Velocity]

It may work... however, the simple piston design would work even better (due to less force pushing the piston against the sealing face) and is simpler to make.

[)DEMON(]

Ok, I know these are nerf but you can learn a little from the design. These are just the type of pistols you are talking about. Looky here: http://www.boltsniper.com/Homemades/BSarmory.htm
And here: http://www.boltsniper.com/BS-9/BS9.htm#design

Enjoy!

[boilingleadbath]

I would either skip the springs entirely (and just use compressed air) or skip the compressed air entierly and just use a spring.

I have an interesting idea for the air-only meathod:
Have a valve (any valve) connect a large chamber to a small chamber. When oppened, the small chamber fills untill it overwelms a burstdisk, and that air accelerates a piston down the pump tube (until it hits a stop).

(chamber)=/=(small chamber)=|====:===========