M4 (Obsolete)

Diameter, inches

8

Height (with spider), inches

Total weight, pounds

Cast TNT weight, pounds

Material

Steel

Components: The metallic Anti-Tank Mine M4 is identical to the M1A1 type except for the booster, the fuze, and the activator wells. The M4 has one activator well on the bottom and one on the side. Since the booster, after loading, becomes an integral part of the mine, and since the M1A1 and M4 boosters and fuzes are not interchangeable, it is especially important that the Mines M1A1 and M4 and their respective fuzes be kept separate. However, the two mines are assembled, armed, and employed in the same manner. The advantage of the Mine M4 is that the internal construction of the M4 fuze makes it safe to re-use, because it is not made more sensitive by repeated light blows.

Fuze: The fuze for the Mine M4 functions on the "cricket" or "oilcan" principle. This means that the firing-pin spring is a convex metal diaphragm which snaps down under pressure to detonate the fuze. The fuze for the Mine M1A1 uses a cocked firing pin spring and shear pins. In appearance, the only difference is that the primer and the de-tonator of the M4 fuze are contained within the fuze body instead of protruding from the bottom as in the M1A1, and the bottom edge is sharp rather than beveled.

Booster: The M4 booster is identical with M1A1 booster, except that it has a flat top with a crossed scar to insure rupture of the booster shell by the detonator, while the M1A1 booster has a cavity in the top to receive the protruding primer and detonator of the M1A1 fuze.

Arming: The safety fork is removed from the fuze by pressure of the thumbs on the prongs.

Color: The bottom and ¾ inch of the side are painted yellow; the rest of the mine is painted olive drab.

Remarks: The Mine M4 is being replaced by the M6.

The M4 also has a protective cover bag.

Figure 238. Anti-Tank Mine M4