High-explosive squash head

High-explosive squash head (HESH),[1] or less commonly known as high-explosive plastic (HEP) is a type of explosive projectile which utilizes a plastic explosive that conforms to the surface of a target before detonating to improve the transfer of explosive energy to the target. Squash head projectiles are similar to high explosive projectiles and are well suited to many of the same targets. However, while HESH projectiles are not armor-piercing, they are capable of defeating armored targets by causing spall which can injure or kill a vehicle's occupants. They were fielded primarily by the British Army as the main explosive round of its main battle tanks during the Cold War. It was also used by other military forces, particularly those that acquired the early post-World War II British 105 mm Royal Ordnance L7A1 tank gun, including Germany, India, Israel and Sweden. In the United States, it is known as HEP, for "high explosive, plastic".

105 mm HESH rounds
Function of HESH-munition
Example of spalling damage caused by HESH shells