The RANGE of hand grenades, in relation to other weapons, is very short. This range depends entirely on the throwing ability of each individual. As a well-trained Seabee, you should be able to throw a grenade, such as the M67 fragmentation grenade, about 35 to 40 meters. The EFFECTIVE CASUALTY RADIUS of a hand grenade is defined as the radius of a circular area around the point of detonation within which at least 50 percent of the exposed personnel become casualties. The radius is about 16.5 yards (15 meters). This radius is small compared to the effective casualty radius of the other Seabee weapons, such as the 60-mm mortar. You must remember, however, that casualties can and do occur at distances much greater than the so-called effective casualty radius.

Except for the M36A2 fragmentation grenade with the M217 impact fuze, the grenades do NOT detonate on impact. All casualty-producing grenades (fragmentation and white phosphorus) have a 4- to 5-second delay fuze. Chemical grenades, except white phosphorus and the M25AZ tear gas grenade, have a 2-second delay fuze element.

You can compare a hand grenade to an ordinary firecracker. It consists of a paper body filled with gunpowder that is set off by a fuze. For example, when you light the fuze, it burns until it reaches the powder, which then explodes and shatters the paper body. A hand grenade functions in the same reamer and consists of the same principal parts: filler, body, and fuze assembly (fig. 12-7).

The body is the container that holds the filler. It may be made of metal, glass, cardboard, or other suitable material. It may 'be circular, cylindrical, or

Figure 12-8.-Functioning of the fuze.

lemon-shaped. Regardless of their makeup and shape, all grenade bodies have two things in common: (1) they are hollow to contain a filler and (2) they have an opening or threaded hole to receive the fuze. Filler is placed in the grenade body. The filler may be an explosive, such as TNT, Composition B (a composite explosive more sensitive than TNT), or black powder. It may also be a chemical, such as tear gas, thermite (incendiary), or white phosphorus.

The fuze assembly is a mechanical and chemical device that causes the filler to detonate or burn. Fuzes that burn are used primarily with chemical grenades; fuzes that detonate are used to explode fillers, such as TNT and Composition B.

When you pull the safety pin from the grenade, the safety lever should be held down firmly by your grip. When you loosen or relieve this grip, the safety lever is forced free from the grenade by a spring, allowing the striker to hit the primer (fig. 12-8). The primer sets off the delay element that burns into the detonator and igniter; this chain reaction is ended by bursting or burning of the filler in the grenade body. This entire action requires only a few seconds, so stay alert when you are handling and throwing hand grenades.