When the T-43 was cancelled, the Soviet command made the difficult decision to retool the factories to produce a new model of T-34 with a turret ring enlarged from 1,425 mm (56 in) to 1,600 mm (63 in), allowing a larger turret to be fitted. The T-43’s turret design was hurriedly adapted by V. Kerichev at the Krasnoye Sormovo Factory to fit the T-34. The resulting new T-34-85 tank had a much better gun and finally, a three-man turret with radio (which had previously been in the hull). Now the commander needed only to command the tank, leaving the operation of the gun to the gunner and the loader.
Although a T-34-85 还是不匹配的一豹，改进的火力使它更加有效。 决定改善现有的设计而不是工具为一个新的允许苏联制造的坦克在这样的数字差异在能力可能被认为微不足道的。 在1944年，国防军只有304豹操作上的东面，同时苏联已经增加T-34-85生产1200坦克每月。
资料来源： T-34 85上的维基百科