I have some 7,92x57 cases and Platz 33 cartridges wich had additional lacquering with transparent brownish varnish above copper platted steel case. For example:
fired case with marked P491 VIIc1 4 39
Platz 33 with headstamp P198 VIIu1 13 38
Platz 33 with headstamp am VIIg1 134 40
Some of this specimens have reloaded mark, and some - no.
What does this varnish means? May be it was transition variant of cases before start of producing steel cases with green varnish? Or may be it was a special covering for improvement the removing fired cases from the barrel in non-automatic weapon?