OK, I have collected a number of components I'd like to assemble into a ballista sized stonebow. For power I'll be using a car leaf spring and building a frame out of 4x4 timber. I want the ballista to hurl "bullets"--gourds, croquet balls, maybe even stones, etc. Since the leaf spring is a continuous piece of steel, I thought I would mount it like a stonebow, with a raised front end, a cutaway center stock, and a raised firing mechanism. (See various forms of stonebow in Payne-Gallwey to see what I mean). Because the spring is finished with closed loops at each end (where the mounting bolts secure it to the car frame), creating a double string and pouch to hold the projectile ought to be fairly easy . . . does anyone out there have any experience with stonebows or other bullet-throwing bows?