A mortar is quite simple and easy to use. Most are muzzleloaders made up of a tube that a gunner drops a bomb into. The tube is usually set at between 45 and 90 degrees angle to the ground. The higher the angle, the shorter the range. When the bomb reaches the bottom of the tube it hits a firing pin. The mortar bomb's weight is enough to set off the firing pin which ignites the round and fires it. Some larger mortars have a firing pin that is set off by using a string instead of automatically.