greener light harpoon gun
A weapon/tool made by the English sporting arms firm of W.W. Greener, the Greener Light Harpoon Gun is a rifle-like device based on the Martini action (best known from the British Army's Martini-Henry rifle) and uses .38 Special blanks to propel a steel harpoon. Though primarily a whaling and fishing implement, the Greener can also be used as a line thrower. Its most prominent appearance in popular culture was in the 1975 motion picture Jaws.