"To: comrade Malyshev, Zaltsmann, Korobkov, Petrosyan. Discuss together and reply with a proposal.
December 10th, 1942
To the Chairman of the Council of People's Commissars of the USSR, comrade V.M. Molotov
Analysis of American armour supplied to the USSR by the People's Commissariat of Tank Production factories and Institute showed that 35 mm thick armour place, produced from steel that is chemically similar to our 8-S steel, does not meet the present requirements of toughness.
The American armoured plate is very brittle, as a result of which plates crack and spall with fragments that are larger than accepted by the technical requirements.
Out of 5 American plates tested at factory #38, 3 cracked into pieces, one produced unfair back-spall, and the other produced fair back-spall. Of 2 plates tested by TsNII-48 at factory #37, both cracked into pieces. Of 8 plates tested at factory #177, 3 failed trials due to cracks and unfair back-spall, 5 plates passed trials, but still gave significant back-spall (though within technical requirements).
The brittleness of American metal is caused by low quality of metal (slating, layering). This low quality can be revealed by fracture tests or at proving grounds. However, the Americans refuse to perform fracture tests and only perform proving grounds tests according to the requirements of the American War Ministry.
Considering the failure of the American armour steel to meet the requirements for 8-S plate, the People's Commissariat of Tank Production turned to the GABTU with a proposal to permit the use of American armour with reduced toughness. The GABTU rejected this proposal, as it did not wish to reduce the protection of our tanks.
Based on the aforementioned information, the People's Commissariat of Tank Production considers it senseless to perform further deliveries of 35 mm armour plate according to present requirements, and asks to instruct the People's Commissariat of Foreign Affairs to inquire about the possibility of introducing additional quality control via fracture testing.
In order to use up the existing stock of 35 mm armour plate that has been delivered to the USSR, I ask you to instruct the GABTU and the NKTP to perform further inspection of the quality of this plate and come to a decision regarding its application.
People's Commissar of Tank Production, Zaltsmann."