Alright, thanks for the help Ill try to come up with a new design. I just want the realism of having a launcher that by its self is nothing and all the power comes from the shells.

I came up with an idea for a Co2 powered air cannon that uses Co2 cartridges to shoot, but I cannot find a valve or a way to puncture the seal on the cartridge that will allow all of the Co2 to escape at once. I don't want something where I have to screw the cartridge into it or attach it to anythin...