In response to ammosmoke, I think thats its a pretty good experimental gun, but I doubt you are going to get a lot of distance from it. If you've got the time and the money, I say go ahead and build it.

Wow, thank you. I thought the specs seemed too small, but GGDT showed it being more than enough. I think that is from some the numbers I used for the valve. Thanks again, thats a huge help.

Alright, so my price estimate wasn't too far off then. The gun I'm building only needs to go 100 or so feet forward and so I'm looking at a 9" length of 2" piping for the chamber, and 12" inches for the barrel. I checked it out on GGDT, and it seemed ok, but I did use some shady numbers for the valv...

I'm trying to build a low-power t-shirt cannon for a small school, powered by normal, 12g canisters of CO2. I'm thinking an over-under orientation, with a piston valve, or maybe a sprinkler valve. I have some experience with combustion and pneumatic spudguns, but I wonder if I'm in over my head. Als...