What is ammunition
Anything that is put into a gun to make it fire a shot is tailed ammunition. Therefore ammunition includes both the bullet that is fired from a pistol and the gunpowder that sends it on its way.
Ammunition may range all the way from the cartridge for a .22 rifle to the giant shell in an 18-inch gun of a battleship,
which can send a mass of armour-piercing steel weighing more than a ton for a distance of twenty miles. Sometimes other explosive weapons used in warfare, such as bombs and hand grenades, are also called ammunition; but usually the word munitions is used to describe all kinds of explosives used in warfare (including ammunition), and the word twin/motion is used to describe only what is used in firearms.
A substance is said to "explode" when it suddenly tries to occupy more space than it is occupying at the time. Either it turns into a gas, usually by burning, or it changes chemically into another substance that requires more space, as in atomic fission. When a substance explodes, it pushes out with great force in all directions. Suppose this happens inside a gun. In every direction but one, the explosion cannot push very far because the hard metal of the gun stops it. But in that one direction, the barrel of the gun is open. So the explosion pushes in that direction, and sends the bullet through the barrel with great force. (The "kick" of a gun is caused by the force of the explosion pushing backward at the same time.) All ammunition must include some explosive.
There are substances that explode by burning, and substances that explode by shock. Gunpowder was the first explosive used in ammunition. It burns very fast. In burning it turns to gas. The gas expands so rapidly that it can send a bullet or cannon ball on its way with great speed. Other explosives have been found that are more powerful than gunpowder. (There is a separate article about explosives.) A chemical called fulminate of mercury is used in many cartridges; it explodes from shock —that is, when it is struck a sharp blow, as by the hammer of a revolver. Usually two different explosives are used in any particular kind of ammunition. There will be a small amount of one explosive and a larger amount of another. When the first, small, charge explodes, it sets off the other.
