A video of the crossbowgun I made. it's a crossbow with a barrel that shoots anything you can fit in it's barrel.
it will shoot a 150 gram projectile 60 meters and a bolt 120 meters, actual ammo comming soon.
it is powered by rubber bands and the barrel is made of PVC.
An instructable is now also available:http://www.instructables.com/id/How-to-make-a-Crossbowgun/