| Top Secret
To Comrade L. P. BERIA According to your order about mounting the 100mm D-10T gun onto «JS» tanks, I have to say the following: 1. At the moment, «JS» tanks armed with the 122 mm main gun are successfully repelling all counterattacks by German tanks of all types at all ranges (i.e. up to 1500 metres); 2. Rearming some tanks with the 100mm gun will cause considerable confusion and problems with ammo supply; 3. Rearming some tanks with 100mm gun will lead to decreasing the firepower of a tank during combat with enemy infantry and pillboxes, because 100mm explosive power is significantly less to the 122mm round; 4. The «JS» tank is limited to 28 122mm rounds or 29 100mm rounds, therefore its ammo load will have to small an increase to take it seriously; 5. There are well known troubles with loading such long 100mm rounds. Moreover, intensive fire from 100mm guns would lead to increased fumes in the fighting compartments of the tank, therefore the real rate of fire of the 100mm gun would be decreased anyway. Taking into account all the comments above, I think that rearming «JS» tanks with the new 100 mm D-10T gun is not expedient. Fedorenko 6.VIII.1944 | 
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