It's a nice cannon. That design has been around a long time. I've made a few except they were solid tubes and filled with air compressor. Still I got a few ideas from it which is always a great learning experiance.
My Son with his. He was about 10yrs old here:
Same design. ALL AMERICAN DAN now owns this one. I got this one off WAR PIG. However all info is good info.
Later,
Blackrain
