Video at the link. Hat tip to Neatorama.
TechEBlog � Feature: World's Largest Shotgun (with Video Demonstration): "The world's largest shotgun aka Punt Gun measures 10-feet long and has a 2-inch barrel. Due to its size and recoil, this gun has to be mounted directly on the punts. Just a single blast could wipe out 50-100 ducks resting on the water's surface."