The Ml8A1 Claymore mine, currently the only mine authorized for use by the Seabees, is used only as an electrically controlled, one-shot weapon. It is used for support of other weapons used in the final protective fire of the unit.

The M18A1 antipersonnel mine (fig. 12-13) was standardized in 1960. It is a directional, fixed-fragmentation mine and is designed primarily for use against massed infantry attacks. The Claymore mine is

Figure 12-14.-The M18A1 antipersonnel mine and accessories packed in the M7 bandoleer.

equipped with a fixed plastic, slit type of sight, adjustable legs, and two detonator wells. The mine and all its accessories are carried in the M7 bandoleer (fig. 12-14).

The mine weighs about 3 1/2 pounds and is 8 1/2 inches long, 1 3/8 inches wide, and 3 1/4 inches high.

Figure 12-16.-The M57 firing device.

The outer surface is a curved rectangular, olive drab, molded plastic case. The front portion of the case has a fragmentation face containing steel spheres embedded in a plastic matrix (enclosure). The back portion of the case contains 1 1/2 pounds of Composition C4 (composite explosive).

When detonated, the Ml8A1 mine projects steel fragments over a 60-degree fan-shaped pattern approximately 6 feet high and 50 meters wide at a range of 50 meters (fig. 12-15). These fragments are moderately effective up to a range of approximately 100 meters and can travel up to 250 meters. The optimum effective range-the range at which the most desirable balance is achieved between lethality and area coverage-is 50 meters.

Figure 12-15.-Range and effects of the M18A1.

Figure 12-17.-The instruction sheet attached to the M7 bandoleer.

M57 FIRING DEVICE

One M57 firing device (fig. 12-16) is issued with each Ml8A1 mine. The device is a hand-held pulse generator. A squeeze of the handle produces a double 3-volt electrical pulse of sufficient energy to fire the electric blasting cap through the 100 feet of firing wire issued with the mine. On one end of the firing device is a rubber connecting plug with a dust cover.

The safety bail on the firing device has two positions. In the upper SAFE position, it acts as a block between the firing handle and the generator. In the lower FIRE position, the generator can be activated.

INSTALLATION AND FIRING

Complete instructions for installing, arming, testing, and firing the Ml8A1 antipersonnel mine are attached to the flap of the M7 bandoleer. The instruction sheet is shown in figure 12-17, and the directions should be carefully followed by users of these mines.