George,
Where the hell did you come across this ?? Ya know, I grew up building crap like this. Tin cans taped together and firing off tennis balls, cutting down shotguns so short the casing stuck out the end of the barrell....(only fired once...) stupid stuff. I have a brother, Greg, that use to make his own black powder and would fire off cannons in the yard, made his own fuse etc.... I would be in heaven living in a town that had a "pumkin chunkin" event ! The trebuchets (sp) are something else too, good stuff !
One of these days, it will be me, the wife, son and my Harley.... 120 acres of sovereign land and a 35 ft. long pumpkin chucker....