The object of the No. 77 hand percussion smoke grenade is to produce an immediate local smoke screen. The grenade is exploded by a detonator in order to make the smoke screen instantaneous. As it is a hand grenade its tactical use is essentially local, but a verry few thrown will produce a dense local smoke screen. Weight ¾ lb.

Remove the screw-on tin plate at the top of the body and ensure the grenade is not pri-med.

Live grenades are issued ready for use except for priming and in no circumstances will they be stripped. The body consists of a tinned plate casing, coloured green, with a screw-on tin plate lid at the top. In the centre of the top of the body is a sleeve for the detonator. The body itself is filled with white phosphorus. In the centre of the lid is fixed a mechanism holder covered by a screw-on safety cap, secured by a piece of adhesive tape. The mechanism holder contains a ball, striker and creep spring and cap holder with a cap. A safety bolt passes through a hole in the mechanism holder and one in the stri-ker, thus keeping the latter in position. To this bolt is attached a length of tape, on the other end of which is a lead weight.

Fig. 19A

Unscrew the lid at the top of the body, keeping the safety cap on. Examine the detona-tor sleeve to see it is free from obstruction. Insert the detonator into this sleeve, closed end first, i.e. open end of the detonator to open end of sleeve. Screw the lid firmly back on to the grenade. The grenade is now ready for use.

Fig. 19B

Having removed the safety cap, the safety tape is kept in position by the fingers. When the grenade is thrown the weight at the end of the tape causes it to unwind, thereby with-drawing the safety bolt. Only the creep spring is now holding the striker apart from the cap. On impact, the striker over-comes the creep spring, fires the cap which sets off the detonator. The explodes the grenade. Immediately on contact with air the white phosphorus ignites and gives off dense smoke for about half a minute.

Any convenient method of throwing may be used, overarm bowling or a lob. If lobbed for short distances, a twist or spin should be given to ensure the tape fully unwinds and falls clear. Before throwing remove the safety cap (the adhesive tape should have already been removed), care being taken that the finger and thumb keep the tape on the grena-de. Then throw as required.

Note. – Small burning particles of white phosphorus will be thrown some distance on the grenade bursting. Serious burns will be caused should these particles fall on the person, as it cannot be extinguished.

Grenades should be inspected periodically, for should the body become corroded the air any may come in contact with the white phosphorus, thereby causing ignition.