The mortar is a smoothbore, muzzle-loaded, high-angle-of-fire weapon. It consists of a mortar barrel with a baseplug and a fixed firing pin for drop firing. The mount consists of a biped with traversing and elevating mechanisms. A spring type of shock absorber absorbs the shock of recoil in firing. The baseplate is a unit that supports and aligns the mortar. For firing, the baseplug of the barrel is seated and locked into the baseplate with the barrel passing through the yoke of the biped mount and secured to the shock absorber. For transporting, disassemble the mortar into three groups: barrel, biped, and baseplate. This weapon may be transported by one crew member without disassembling it.

The mortar is fired by inserting a complete round into the muzzle, fin assembly down. The elevation of the barrel causes the round to slide toward the base of the barrel. On reaching the base, a propelling charge on the round is ignited by the firing pin. The pressure of the gas produced by the burning propelling charge drives the round up and out of the barrel. The fin assembly stabilizes the round in flight.

The mortar can deliver fire at ranges up to approximately 3490 meters. The sustained and maximum rates of fire are related to the type of round and charge being used.

The complete mortar weighs 46.5 pounds in the conventional mode and 18 pounds in the hand-held mode. This includes the cannon (14.4 pounds), the biped (15.2 pounds), and the M7 baseplate (14.4 pounds) and the M8 baseplate (3.6 pounds). The overall length is 40 inches.

Figure 14-2.-M225 cannon.