Critical Mass,critical mass wrote: ↑28 Dec 2018 12:06Attached are Zahlentafel 9a and-b from BAMA RH8-1319 ("H. Knüppel, Entwicklung von Hochleistungsgranaten auf Grundlage des Homogengeschosses", originally classified SECRET, dated 1942, reporting on the improvements of APC mass production techniques for Pzgr.39 series APCBC-HE, unpublished primary source).
Notice that the lower table shows the effect of optimum hardness. The upper tabulation therein was for tests employing a much higher hardness (Rc =64.0 nose and Rc=60.0 core), which lead to early break up and outright shatter in some cases. The slight temper of the german AP towards a nose hardness =61.0 and core 59.0 ideally, was exactly on the sweet spot between optimum hardness but acceptable toughness to prevent early break up.
Post ww2, the germans were extremely critical about the british adoption of higher hardness for their AP-shot. They claimed this gives raise to formation of brittle carbide networks in the head of the shell, which are relatively easy to break up. The british thought that the use of a cap would prevent shatter, which it did but they failed to understand that the germans consistently differentiated between shatter failure and break up failure, and that they tested these shells with cap, too.
The upper tabulation, Zahlentafel 9b shows experimentation in the optimum alloying with heat#8079 beeing markedly superior, the results of which I reported in a previous memo. Notice that these are actual test records, not smoothed penetration chart interpretation of the actual tests.
On the base of these tests, WaPrüf issued updated specification standarts for manufacturing of the Pzgr39 to all manufacturers, replacing their respective heat treatments during mid 1942. The first projectiles arriving in not before summer / autumn 1942 on the eastern front.
On page 2 a Leuchtgas-Sauerstoffbrenner is mentioned. Usually this device is used to cut steel in a cost-effective but not very accurate manner.
Casting #8079 has a CEV value greater than 0.92.
Was this device used in order to get the approximate shape, which could be corrected in a subsequent step, or in order to reheat the metal?