SpudFiles

i used a large (not sure of exact size) fire extinguisher as the pressure chamber, connected tow a ball valve, which is then connected to a copper pipe barrel, this is a very early design, and i hope to make the extinguisher into an air chamber, connected to a much smaller pressure chamber, and make this into semi auto gun, i also really need to work on the valve, as the ball valve is not quick enough, i am going to try to build my first piston valve on this cannon aswell.

(its not very impressive

heres some photos

awesome quick design, but if you have a couple bucks to spend get a qev( quick exhaust valve) or even better dust collector valve!!!

have fun

Actually, the dust collector valve wouldn't work well with an unmodified tank like this. Get a QEV and make it semi auto. Lots of info and numerous ways to set it up.

Thanks for the ideas, i will probably make it spemi auto with a qev

they are not that expensive, i got mine for like 8$ look on ebay ^^

Pretty much the same as my first cannon, but I upgraded it with a longer barrel and a QEV, link's in my sig if you want to have a look
Where's the fill valve though? And what pressure are you using?