Medium Tank T-34/85 Model 1943
In August 1943, at a session of the GKO, the implications of the battle at Kursk were studied. The German tanks not only had thicker armor but their excellent guns gave them a 'longer arm'.
Work on an 85mm-armed T-34 assumed considerable urgency.
Three teams worked on the new weapon :
- The team of Gen. F. Petrov, who had developed the 85mm D-5 gun used on the KV-85, SU-85 and IS-1, and
- that of V. Grabin of the TsAKB (Central Artillery Design Bureau) in Moscow prepared designs.
- A third project at Zavod Nr, 92 in Gorki, was under study by a 23-year old engineer, A. Savin who had taken charge in place of Grabin.
At the end of 1943, all three prototypes were installed in two-man turrets on T-34 chassis and sent to the Gorokhovieski Proving Grounds outside of Gorki for trials.
The turret was clearly too small for efficient handling of the gun and the guns themselves clearly had problems.
In the meantime, the design bureau at Krasnoye Sormovo Zavod Nr. 112 in Gorki, under V. Krylov, began final preparation for the production of a three-man turret.
The larger turret, designed by V. Kerichev, easily accomodated the 85mm gun.
Unfortunately, it was soon realized that the winning ZiS-53 gun, as designed, would not mate properly with the new turret.
Both design teams were insistent on staying with their own scheme.
Finally, GKO had to step in, ordering Grabin to modify his gun to fit.
On 15 December 1943, even though it existed only in the form of two unarmed prototypes, the new T-34-85 was accepted for service use in the Red Army and production orders were given.
Firing tests of the modified ZiS-53 85mm gun revealed more problems.
As a stop-gap measure, the runner-up D-5T gun was selected for use in the first production batch of T-34-85 Model 1943s. These entered production at Zavod Nr. 112 in January 1944.
That same month, the modification of the ZiS-53 was taken in hand by Petrov, Savin and Grabin.
The resulting ZiS S-53 Model 1944 (S for Savin) finally resolved the gun's problems and was approved for production.
In March 1944, it replaced the D-5T on the assembly lines at Krasnoye Sormovo resulting in the standard T-34-85 Model 1944.
Source : Zaloga/Grandsen, »T-34 in action«