Correspondence about mounting the 100mm D-10T Gun on "JS" tanks (Letter 1)

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To Malyshev (convocation)
Ustinov
Fedorenko
Yakovlev
Kirpichnikov
Borisov
Petrosiants
Vannikov

Work out the combined offer for a further report for Com.Stalin.
You have three days.
L. Beria 3.VIII.44

To comrade L. P. BERIA
About mounting the 100 mm D-10T gun on «JS» tanks designed by Factory #9 NKV.

From 1 to 6 July this year, repeated trials of the «JS» tank armed with the 100 mm D-10T gun (designer Com.Petrov) have been conducted at the Gorokhovetskiy proving ground GAU RKKA.

The 100 mm D-10T from Factory #9, mounted on the «JS» tank have successfully passed all tests and, according to the conclusion of the special Commission, the gun can be recommended for service.

The following benefits gained if the «JS» tank is armed with the 100 mm D-10T instead of the 122 mm D-25T are:

1. Practical rate of fire of the 100 mm D-10T gun is about 5–8 shots per minute, instead of 2–3 shots with the 122 mm D-25T gun;

2. The «JS» can accommodate 29 100-mm rounds instead of 28 122-mm rounds for the D-25T gun;

3. The absent a muzzle brake on the D-10T provides better working conditions for the gunner;

4. The tank with a 100 mm D-10T weighs 500–600 kg less than a tank armed with the D-25T. That difference can be exploited to increase armour protection for most vital elements of the tank;

5. Due to the smaller dimensions of the 100mm D-10T gun breechblock, working conditions for the crew are better.

Meanwhile, armour penetration of the 100 mm D-10T gun at all combat ranges (up to 2000 metres) is superior to the 122 mm D-25T.

Taking into account all the comments above, especially the good rate of fire of the 100 mm gun, which would significantly increase the JS's firepower, I believe that from September-October of the current year «JS» tanks must be armed with the 100 mm D-10T gun instead of the 122 mm D-25T gun.

That rearming won't cause any trouble for either the NKV or the tank industry.

I have attached two photos of the «JS» tank armed with the 100 mm D-10T gun.

Awaiting your orders.

V. Malyshev 8.VIII. 1944