By the late 1950s, Soviet commanders realized that the T-55's 100 mm gun was incapable of penetrating the frontal armor of newer Western tanks like the Centurion and M48 Patton with standard AP shells. While 100 mm HEAT ammo could have accomplished the task, they were considerably more expensive and required more training of tank crews for proper use. It was then decided to simply up-gun the T-55 with a 115 mm smoothbore cannon, capable of firing APFSDS rounds. Experimental trials showed that the T-55 was inherently unsuited to mount the larger new cannon, and work therefore began on a new tank. The bigger gun required a bigger turret and turret ring to absorb the higher recoil. This in turn necessitated a larger hull, as the T-55 hull was simply too small to accept the new turret. The T-62 thus took shape, marking an evolutionary improvement upon the T-55.
