High explosive squash head : HESH

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 doesn't 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.