Well, ive decided upon my new project.  I think by the picture you'll get a good feel for how it works.

Everything is out of proportion, but I think youll understand the general idea.  Steps of operation:

1.)  Make sure Hybrid Push Button ASA is in the closed postion
2.)  Open up standard ASA for a few seconds.
3.)  Close standard ASA
4.)  Load paintballs into front of barrel - ill expiriment with multiple paintballs.  Im hoping to be able to fire off about 10 at a time so I can just use 10 round tubes.  It dosent need to be at 300 fps, im just hoping for a fair amount.  And yes, the barrel will be longer on the final product.
5.)  Open Hybrid ASA to fire gun.
6.)  ?????
7.)  Profit.

Im hoping this will be able to fire at decent velosities.  If you have any input into this area, id appreciate your opinion on if you think id be underpowered.  Someday, I may put a reg in place of the expansion chamber so I can control velosity somewhat.  The normal expansion chamber is there mostly just to hold air so I can discharge more air with a single shot.  I want to keep this fairly inexpensive right now, but if it works ill definitly look into the reg.  Id appreciate any input you guys have into improving this basic design and any comments if there is a different material i should be using.

kickinwing2010 wrote: Personally I would pick up some compressed air then use a regulator with a ball valve and a holding tank. that way when you close the front valve the holding tank will fill up with the correct amount of pressure every time. the you load the barrel and throw open the front valve and it will fire.

Well, I wanted something like this, but I dont know where to find a holding tank.  I do have compressed air, but I do not want to spend the money for another reg.  CO2 will produce more power than compressed air will, anyways.  Anyone know of where I could find a holding chamber type thing to take the place of the expansion chamber?  More capacity would definitly help.

Stang909 wrote: dont even get a reg just get a fixed high output tank, have the tank hooked up to a ball valve and then build it like a potatoe gun, my friend has made one of these with the setup i explained and it worked pretty well, and if your worried about velocity then dont port it that way you get more build up behind the paintballs

Okay, well, i have a preset hp crossfire 68/45, so thats not a problem.  Ill look into trying that.