The Pressure firing device M1A1 is a standard firing device which can be threaded to all of the stan-dard anti-personnel mines, hand grenades, and to the bangalore torpedo.

GENERAL:

This is a mechanical device designed for firing explosive charges by means of pres-sure. A pressure of 20 pounds or more applied to the trigger pin will actuate the device. Various extensions for attachment to the pressure head, are issued with the device in order that it can be adapted to varying circumstances.

DESCRIPTION:

The principal parts of the device are the body, trigger pin and pressure head, striker spindle, standard nipple base, safety clip, and safety pin. The projection of the trigger pin which extends down into the body has two holes of varying diameter with an inter-connecting slot. The hole toward the bottom of the trigger pin is the smallest. The striker spindle has a circumferential groove around the part that extends through the trigger pin. When the device is set, the trigger pin is held up either by a clip or just its spring and the grooved part of the striker spindle is engaged in the smaller hole on the trigger pin. In this position the striker spindle is locked and cannot fire.

INSTALLATION:

Keeping safety clip and pin in position, remove base containing percussion cap. Re-move cardboard protector tube from base. Place firing device in position at location where it is to be used. Slide open end of non-electric cap over projection on base and crimp, using cap crimper. This should be done carefully in order to insure a watertight joint. Screw base, with non-electric cap attached, to device. Prime charge. When primacord is used, tape looped end of primacord to non-electric cap and run the other end to charge. If primacord is not used, insert non-electric cap into block of explosive. Remove safety cap. It should pull off very easily. A sudden jerk may cause the striker head to spring forward. If safety clip does not pull off easily, check installations to make sure that there is not already enough weight on trigger pin head to cause device to function immediately when safety clip is removed. Remove safety pin from housing adjacent to cap base. This pin must be removed last. As long as it remains in place the device cannot possibly fire.

OPERATION:

When the device is armed, the striker spindle is engaged in the lower (smaller) hole in the trigger pin and the pin in turn is held up by the trigger pin spring. If a pressure of 20 pounds or more is applied to the pressure head, the trigger pin is forced inward and the larger hole in the projection of the pin is moved in line with the striker spindle. The head of the striker spindle can pass through this hole, and the striker is free to be for-ced against the percussion cap by the compressed striker spring.

REMARKS:

(1) When the trigger spring removed, a pressure only 5 pounds will actuate the de-vice. The number of ways that this device can be used is limited only by the ingenuity of the users. Among its may uses are to fire booby traps, to set off an anti-personnel mine, to make removal of anti-personnel or vehicle mines in the vicinity more difficult, or to activate anti-tank mines, so they will detonate when stepped on.

(2) The extension rod or the three-pronged extension can be threaded into the pressure head as circumstances warrant their use.