The remainder are intended to be thrown by hand.
Hand grenades can be of two classes, Heavy and Light. Heavy grenades weigh about 2 lbs. and light about 1 lb. It is considered that a man can throw a 2-lb. weight about 30 yards and a pound-weight about 50 yards. Heavy grenades project fragments of some weight a fair distance, while light grenades rely for effect principally on the blast of detonation.
The effective area of a light grenade is mainly local, 6 yards diameter, but when possible it should not be thrown less than 20 yards in the open, as stones, etc., thrown up by the explosion would be dangerous to the thrower.
The danger area of the heavy grenade is about 30 yards in diameter, and, therefore, it should not be thrown less than 25 yards in the open. With both grenades the thrower should cover the eyes at the moment of explosion and protect himself, as small fragments of metal may carry further than the distance mentioned.
The types of hand grenades (b), (c) and (d) differ fundamentally in the means by which ignition is effected; (b) explodes instantaneously on impact (by percussion), while (c) and (d) are fired by time fuse, which is lit in (c) by spring action releasing a trigger at the moment the grenade leaves the thrower’s hand, and in (d) by an independent action on the part of the thrower before throwing the grenade.
In the case of (b) it is necessary that the grenade fall head first. This is done by the backward pull in the air of the streamers attached to the handle. In using this grenade it is, therefore, necessary to see that the streamers are opened out and free—before throwing, and to throw the grenade well upwards.
In the case of (d) the total time of delay is slightly over 5 seconds, so that from 1½ to 2 seconds should be used in throwing. If thrown hastily it may arrive at the mark 3 seconds before exploding and allow it to be returned by the enemy.
When handling detonators for grenades, it should be remembered that the detonator by itself is capable of blowing the hand off, so it must be carefully handled, and if an igniter is accidentally fired it should be thrown a few yards clear of any one in the neighborhood. When the igniters and detonators are in the grenades reasonable care should be taken to avoid rough usage as violent treatment might fire the grenades, even in the safe position.
Grenade .303-inch, Short Rifle, No. 3, Mark 1 (J. pattern). Description: The grenade consists of a steel body filled with explosive. Down the centre of the explosive is a brass tube into the forward end of which the detonator is inserted. The rearward end of the body is closed by the base piece which carries the needle pellet, two retaining bolts, wind vane and releasing socket with safety pin. To the base piece is fixed a base plug carrying the spring clip and a 10-inch steel rod.
The action of the grenade is that, the safety pin having been removed, on firing the releasing socket sets back from under the wind vane, which is then revolved by the wind pressure as the grenade travels through the air. After a few turns of the vane the retaining bolts are no longer held in position by its inner surface.