Original Item: Only One Available. These 1/2 lb C-4 bricks were used by various Army, Navy, and Marine engineers and demolitions units. C-4 is very stable and insensitive to most physical shocks. C-4 cannot be detonated by a gunshot or by dropping it onto a hard surface. It does not explode when set on fire or exposed to microwaves. Detonation can only be initiated by a shockwave, such as when a detonator inserted into it is fired. When detonated, C-4 rapidly decomposes to release nitrogen, water and carbon oxides as well as other gases. The detonation proceeds at an explosive velocity of 8,092 m/s (26,550 ft/s).

A major advantage of C-4 is that it can easily be molded into any desired shape to change the direction of the resulting explosion. C4 has high cutting ability. For example, the complete severing of a 36 centimeters (14 in) deep I-beam takes between 680 and 910 g (1.50 and 2.01 lb) of C4 when properly applied in thin sheets.

This 1/2 C-4 block is completely empty and totally Inert. This example is in complete compliance per the BATF regulations. Not Available For Export.

This thick cardboard block is complete with both end tabs present. This example appears to have never been used or rigged at some point to be used. All markings are still 100 percent visible and able to be ready easily:

HIGH EXPLOSIVES
COMPOSITION C- DANGEROUS
UNITED STATES ORDNANCE DEPARTMENT
1/2 POUND NET

The box measures approximately 6 ¼” x 1” x 1 ½” and is complete and ready for display!

U.S. soldiers during the Vietnam War era would sometimes use small amounts of C-4 as a fuel for heating rations, as it will burn unless detonated with a primary explosive. However, burning C-4 produces poisonous fumes, and soldiers are warned of the dangers of personal injury when using the plastic explosive.

Among field troops in Vietnam it became common knowledge that ingestion of a small amount of C-4 would produce a "high" similar to that of ethanol. Others would ingest C-4, commonly obtained from a Claymore mine, to induce temporary illness in the hope of being sent on sick leave.