High explosive squash head, also known as
HESH or
HEP (in US usage, for high-explosive, plastic), rounds are a type of anti-
tank explosive. On impact the
plastic explosive in the shell spreads out to form a disk on the surface of the
armor, which is then detonated. The explosive does not penetrate the armor directly, instead the
shock wave travels through the armor and causes flakes of metal to
spall[?] off and fly around the interior of the tank. HESH shells will rarely actually penetrate the armour.
Developed and used only by the British, HESH was used for some time as a competitor to the more common HEAT round. In more recent times HESH has become less common.