The British 165mm Demolition gun, officially known as the Royal Ordnance L9 (the L9A1 gun being a later variant)

The BL 165 mm (6.5 inch) was capable of firing a 64 lb High Explosive Squash Head

High explosive squash head

High explosive squash head is a type of explosive ammunition that is effective against buildings and is also used against tank armour. It was fielded chiefly by the British Army as the main explosive round of its main battle tanks during the Cold War...

 (HESH) demolition projectile over distances up to 2,400 metres. It was mounted on Royal Engineers

Royal Engineers

The Corps of Royal Engineers, usually just called the Royal Engineers , and commonly known as the Sappers, is one of the corps of the British Army....

 AVRE

Avre

Avre may refer to:*Avre , a river in northwestern France, tributary of the Eure*Avre , a river in northern France, tributary of the Somme*Armoured Vehicle Royal Engineers, a military vehicle of the British Army...

 versions of the Churchill tank

Churchill tank

The Tank, Infantry, Mk IV was a heavy British infantry tank used in the Second World War, best known for its heavy armour, large longitudinal chassis with all-around tracks with multiple bogies, and its use as the basis of many specialist vehicles. It was one of the heaviest Allied tanks of the war...

, Centurion tank

Centurion tank

The Centurion, introduced in 1945, was the primary British main battle tank of the post-World War II period. It was a successful tank design, with upgrades, for many decades...

.

The American M728 Combat Engineer Vehicle

M728 Combat Engineer Vehicle

The M728 Combat Engineer Vehicle is a military engineering vehicle based on an M60A1 Patton main battle tank chassis with a hydraulically operated dozer blade mounted on the front effectively functioning as an armored bulldozer, plus an A-frame crane boom hinged on either side of the turret and a...

 variant of the M60 Patton

M60 Patton

The 105 mm Gun Full Tracked Combat Tank, M60, also known unofficially as the M60 Patton, is a first-generation main battle tank introduced in December 1960. It was widely used by the U.S. and its Cold War allies, especially those in NATO, and remains in service throughout the world today...

 tank used a XM-135 gun patterned after the British 165 mm.

The gun's primary purpose is for clearing obstacles such as walls, fences, roadblocks, bunkers, etc. or for destroying buildings. It is not effective for anti-personnel or anti-tank use.

The HESH

High explosive squash head

High explosive squash head is a type of explosive ammunition that is effective against buildings and is also used against tank armour. It was fielded chiefly by the British Army as the main explosive round of its main battle tanks during the Cold War...

 rounds, which included 40 lb of C-4

C-4 (explosive)

C4 or Composition C4 is a common variety of the plastic explosive known as Composition C.-Composition and manufacture:C4 is made up of explosives, plastic binder, plasticizer and usually marker or odorizing taggant chemicals such as 2,3-dimethyl-2,3-dinitrobutane to help detect the explosive and...

explosive, are more like tossed grenades than large bullets. When fired, the massive round may be observed with the naked eye flying through the air in a high arc, landing with a huge explosion.