At their inception in 1916, the British Mark I tank proved nearly impregnable to standard rifle fire. The first attempt at boosting the power of German infantry rifles was the "reversed bullet". This utilized the same case and bullet as a normal round, except with the bullet seated backwards and more propellant added to the cartridge. When fired, the blunt end of the bullet hits the target first. The bullet does not break apart against armor plating like a normal bullet would. When used against World War I tanks, it sometimes penetrated into the tank compartment, but often it severely distorted the plate armor of the tank. This caused a spray of metal fragments (spall) that hurt or killed the crew of the tank, making it just as effective as full penetration of the compartment. At short range, armor required a minimum thickness of one-half inch in order to stop a reversed bullet. The Germans also used reversed bullets at short ranges against French infantry.
The reversed bullet sometimes damaged German rifles, often injuring its users. This made it unpopular with German infantry. Later in World War I, the Germans developed the armor-piercing K bullet for use against heavier British tanks.
- Paschall, Rod. (1994). Defeat of Imperial Germany, 1917-1918. Da Capo Press.