A couple of pictures of an old cartridge.
Here is a clearer picture of that hs:
I know of about a dozen 8.15x46R hs variations using the “NORM”.
K = Karlsruhe (DWM factory). This is a post 1909 hs format.
FYI, I can be a bit more specific with that production period. DWM used that single letter factory code on sporting ammunition (which was allocated at the 1909 Erfurt conference) from c1910-c1914, not after WW1.
Here are some notes on NORMalised and the 1909 Erfurt Conference single letter hs codes: