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Tungsten Woes

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"To Deputy GAU Chief, Major-General Hohlov

In the end of August of this year, NII-24 received samples of captured German 37 and 47 mm subcaliber armour piercing and welded shells. After their analysis, the institute gave a conclusion on the design and metal, and sent all materials regarding subcaliber shells to your address on August 25th, 1941.

The institute made the following conclusions:
  1. It is necessary to test shells of this design.
  2. Perform trials on shells produced from non-deficit materials. Experimental 45 and 76 mm subcaliber shells based on the Komissan prototype were tested at the Sofrino proving grounds with the following results:
    1. Thanks to the decrease in mass, the muzzle velocity greatly increased: up to 1010 m/s for the 45 mm gun and 550 m/s for the 76 mm regimental gun mod. 1927.
    2. However, this increase in velocity did not result in increased penetration. For example, the 45 mm gun could not penetrate a 50 mm plate from 200 meters (a dent was formed).
This performance can be explained by the fact that the core of the shell should be produced from a special alloy, analogous to the one used by Germans (75% tungsten, 2% cobalt, 4% carbon), or it will shatter into small pieces on impact with armour, even if it's made from high-carbon instrumental steel with vanadium. At the same time, members of UVNA and Artkom insist that the German shells be reproduced using the aforementioned alloy. NII-24 protested, giving the following reasons:
  1. There are no tungsten reserves. Even if results of testing are successful, these shells cannot be practically put into production.
  2. These cores can only be produced with grinding tools are are available at only a few factories.
Despite these reasons, UVNA sent a letter on September 19th, 1941, again bringing up the subject of producing subcaliber shells, with the motivation that 3rd Department of Artkom has a deal with the Institute of Hard Alloys to produce the required amount of alloy, similar to the one used in German samples.

Our colleague from the metals laboratory was also in this institute, and he was told that it is theoretically possible to produce this alloy, but the chief of the special laboratory comrade V.Ya. Raskin explained the cost at which this alloy would come. The price is as follows: the amount of alloy required to make one core for a 76 mm subcaliber shell is the same as for 30 aircraft factory cutting tools.

The Artkom representative, comrade Lyagoshin, tried to prove that once we can test a copy of the German shell we can look for a substitute to tungsten. Engineer Lyagoshin must not have understood that the main component of the alloy must be an element that, when alloyed with carbon, gives a density of 15.0 and Rockwell hardness of about 80. In any other case, the result will be the same as NII-24 observed with Komissan shells.

Based on the above, NII-24 is categorically against the UVNA proposal to produce experimental shells based on the captured German subcaliber shells.

If UVNA desperately needs to test subcaliber shells, they can perform tests with captured German subcaliber shells, which GAU has plenty of.

NII-24 Director Averchenko
NII-24 Chief Engineer Matyshkin"

Via kris-reid.

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