When I was with a friend who lives in the Italian mountains I came up with the idea to built a slingshot rifle. Not having the best of tools I had to settle for some less work quality as I am used to. Still it shoots fine and at 15 meter the groups are about 10 cm in diameter. By now it does not use tubes anymore but flatband gold. The trigger system works really nice. There is a little hole in the piece that holds the pouch in place so that the projectile is always shot from the same place, thus improving accuracy. Thanks Joerg for the band calculator. It was really helpful. Hope you like it. Cheers, Adrian.