This efficient weapon operates on the same principle as the harpoon guns used in whaling in that it has a line uncoiling from a tank with which to retrieve the harpoon as well as the prey. Appearance and size are similar to a conventional gun with the exception of the tank for the line. The “barrel” consists of a length of cold-rolled steel channel secured to stock with 3 countersunk screws, and has a guide near “muzzle” with a-groove for harpoon shaft to raise one of the barbs above bottom of channel.
Plans and descriptions
in jpg and pdf HERE
Retrorambling 