A speargun is used by underwater fishermen as a fast way to catch their prey. There are many different kinds that have been adapted over the years but the main two kinds are the pneumatic and rubber band powered.
The rubber type use rubber either in the barrel, a rubber band or both. They are the cheaper kind but still effective and easy to use for beginners and experts alike. The rubber speargun is usually made from wood or sealed metal tubing, sometimes though both materials are used. The barrel comes in two shapes, either rounded or rectangular. The circular kind have a separate fitting known as a muzzle fitted either inside or over one of the ends so that you are able to fit the bands. The rectangle kind has slots to fit the bands.
The bands or rubber of this kind are what propels the spear through the water at the chosen target. The ends of the bands or fitted rubber have a wishbone shaped fitting that alter according when the rubber is pulled to load the spear. When the trigger is pulled the tension of the rubber is released thus sending the spear off at great speed.
The pneumatic kind works by air power. Its spear is thicker and is placed inside a barrel where the air pressure is loaded by hand. It must be pumped until the pressure is equal to that of a strong band, by which point it is forced downwards into position. It is then released by the trigger to fire.
Both kinds of gun need to have a trigger to release the tension or pressure inside the chamber. Without the trigger neither would be able to work.
Spearguns are used for sports spearfishing, underwater target shooting, a weapon by some and of course for what they were originally intended. Catching fish for either their family or to sell to make a living.