Please permit me to throw another �cat� into the equation. Eickhorn was a major player, and probably had stocks of pre manufactured parts waiting to be assembled. Voos was not, and seems to have done a lot of small scale hand work as needed. Speaking generally, there is no question that copper was restricted for military use (dress weapons don't count) in the late 1930's. Followed by aluminum, with zinc being the metal of choice until the end of series production in 1942.
And please don�t let the images I posted make unclear my intent. Unfortunately, to enhance them enough to be able to show them side by side, it created a lot of computer generated �artifacts� which does make it look more like an electropencil. That is why I asked for more images because I knew that there was a discrepancy between the ones Rob NL posted and the comparison.
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Eickhorn was a major player, and probably had stocks of pre manufactured parts waiting to be assembled. Voos was not, and seems to have done a lot of small scale hand work as needed. Speaking generally, there is no question that copper was restricted for military use (dress weapons don't count) in the late 1930's. Followed by aluminum, with zinc being the metal of choice until the end of series production in 1942. 