The hand grenade has been used as a weapon in warfare since the fifteenth century. During the seventeenth and eighteenth centuries specially trained men known as grenadiers were armed with hand grenades. In World Wars I and II all armies had them and they have been employed effectively in the more recent conflicts including the Korean and Vietnamese wars and in guerrilla activities all over the world.
A grenade is a small explosive bomb with the first grenades looking like pomegranates. Presently, there are fragmentation granades with cast iron or steel containers that shatter into many pieces when they explode and chemical grenades comprising steel containers filled with phosphorous, tear gas or smoke producing materials. These grenades may be thrown by hand, fired from a hand-held weapon or hurled from a grenade launcher.
The modern hand grenade typically comprises a cast iron or steel body which holds the explosive charge, a detonator which ignites the charge, a time delay train leading to the detonator, a primer, a striker, a striker spring, a safety lever and a safety pin. The striker is always in the cocked position from the time of manufacture with the striker spring under pressure. A catch at one end of the safety lever restrains the striker so long as the lever is held against the body of the grenade, and the safety pin secures the position of the safety lever until the pin is pulled.
When using the grenade it is grasped in the throwing hand with the safety lever held against the body of the grenade. The safety pin is then removed. As the grenade leaves the hand during the course of its being thrown toward a target, the safety lever springs outward releasing the striker. The striker impacts the primer igniting the time delay train. The time delay train begins burning at one end and the burning progresses toward the opposite end at a relatively low rate of travel. After a predetermined period of time, the burning reaches the detonator, the detonator fires and ignites the explosive charge causing the body of the grenade to explode, scattering fragmented shrapnel over the target area. If the device is a chemical grenade it gives off smoke or tear gas when ignited.
Grenades of this type have been made almost entirely of metal, including the body, the safety lever and the striker mechanism. Fabrication from metal has been necessary in order to assure safety for the user. Because the striker is always in the cocked position, materials have had to be employed that are not subject to creepage which might result in a premature release of the striker mechanism. Fabrication from plastics has thus been precluded and the cost of the grenade has accordingly remained relatively high.
Even when fabricated from metal, the present grenade design with its normally-cocked striker is inherently unsafe. From the aspect of safety an improvement could be achieved in a design configuration employing a striker mechanism that is not cocked until use is imminent.
An improved grenade design is thus much to be desired. In particular, such a design should be made inherently safe for the user even when fabricated from inexpensive plastic materials.