Potato Cannon

A few week's ago I finished making my potato CANNON with my dad,and I can't
wait to fire it.The potato cannon is 7ft long, and can hurl a potato 100yrds, and rip holes in plywood.My Grandpa is very worried, but as long as the igniter doesn't blow
out of the holder it should be safe.
There are two types of fuel you can use,there's propane and hairspray,
propane is more flammable, but more dangerous, and sometimes it can break
the wall of your cannon.In my opinion, hairspray is better for various
reasons like you won't shoot flaming potato bits everywhere, and your
cannon won't blow up, and you won't be knocked down from the force of the
explosion in the combustion chamber. By the way don't worry I will have
pictures soon.