DESCRIPTION. The complete round which is made up of the hollow charge stick grenade and the propellant, is fired from the 3.7-cm P.A.K. gun. (See fig. 303.)

The stick grenade has a steel rod which fits into the bore, and a concentric perforated sleeve which fits around the barrel of the gun. A pressed steel cap forms the nose of the grenade giving it the required stand-off distance. The hollow charge is at the rear of the steel cone and consists of two blocks of dinitroanoline with TNT. Two detonators are set in the base of the grenade, one facing in each direction. A nose fuze of the instantane-ous percussion type and a tail fuze also instantaneous are present.

The steel rod which fits into the bore of the gun is a hollow tube closed at the base end. The base fuze is a percussion type fuze very sensitive to shock. It is armed by setback which release a spring loaded detent allowing a steel ball to move away away from the striker. Upon impact the striker moves forward against the action of a very weak creep spring.

The nose fuze consists of a striker held away from the primer by a creep spring and a coiled spring. Around the coiled spring is an inertia pellet resting onm four fingers of a stirrup spring fixed in the base of a stirrup spring retainer. The inertia pellet has a groove cut around its internal circumference.

Two detonators are located at the base of the main charge. One detonator faces toward the nose fuze to receive the flash from there, and the other detonator faces the tail fuze to receive its flash.

The propelling charge is contained in a steel cartridge case. The charge consists of die-thylene glycol dinitrate tubular stick powder with an igniting charge of nitrocellulose gra-nular powder, and a percussion type primer consisting of mercury fulminate and black powder.

OPERATION. On discharge the inertia pellet of the nose fuze is driven downwards and the ends of the stirrup spring are forced into the grooves of the inertia pellet thus hold-ing it down. The clock spring is now held in position by the collar of the striker pin and the stirrup spring retainer. On deceleration the clock spring flies outward, assisted by centrifugal force, into the recess in the fuze body. At the same time the base fuze is be-ing armed. In the event of direct impact the nose fuze will function the grenade, but in the event of graze action, the base fuze will function the grenade.

Figure 303 – 37-mm Hollow Charge Rifle Grenade