Description: This grenade may be thrown by hand or projected with the 50-mm. grena-de discharger, Model 89. The incendiary filling is contained in brass body which may have a propelling charge on the base. The fuze is identical to the one used in the types 91 and 97 fragmentation hand grenades.

The steel propellant container is 1 1/4 inches long, 1.02 inches in diameter, and has six perforations in its walls. It is screwed into the base of the body. A perforated plug screws into the base of this container and in a cavity in this is a percussion cap. Two flash holes head through the percussion cap holder to a small quantity of black powder. A perforated steel disc covers the plug and inside the propellant container proper is a copper cap containing flakes of nitrocellulose propellant powder.

Operation: The firing pin must first be threaded down into the inertia weight. The safety pin must then be withdrawn. If the grenade is to be thrown by hand, it is necessary to strike the inertia weight on some hard object thus driving the firing pin into the primer to ignite the delay train.

If the grenade is to be fired from the grenade discharger, or knee mortar as it is some-times called, the grenade with propellant container is dropped base first into the dischar-ger. When the trigger mechanism of the discharger is operated, its firing pin strikes the percussion cap igniting the propelling charge which propels the grenade. Force of set-back causes the firing pin in the grenade fuze to compress the creep spring and hit the primer to ignite the delay train.

Figure 177 – 1/2-kg. Incendiary Hand or Mortar Grenade.