whipped this cannon up out of some spare parts a couple days ago, operates by filling the cannon with a burst disc loaded to less than bursting pressure, closing the ball valve and filling the bigger tank with more. Or, can be operated using the ball valve alone. I haven't really used it much yet, but seems to have some pretty decent power for such a simple cannon, and is comfortable to use.
I've been shooting Nerf mega darts with wadding and the heads filled with hot glue and at a guess it's probably getting round the 200fps mark at 50psi. I'd be interested to see what it could do with a potato at 150psi. In future I might add a bipod and a spring to the ball valve, but otherwise it's fun as it is.
