Spigot mortars

Spigot mortars are mortars of an unusual design. Rather than a tube attached to a base plate, it consists of a rod or "spigot" attached to the plate. The tube used to concentrate the explosive gasses created to launch the mortar shell is attached to the projectile instead. The shell tube is place around the spigot and it is dropped as is usually done. The length of the spigot is such that it strikes the firing pin on the shell just as the end of the tube touches the base plate. This fires the shell, leaving the tube behind. The advantage is that the mortar itself is lighter and more portable. The disadvantage is that the shells are heavier and more complex. Unless the soldiers using a spigot mortar carry only a few shells, the conventional design is more advantageous.