I suspect this is ‘Military Issued’ …and the DH serial code, subsequently ‘ground off’ the back…after the War What size is the chrome case ?
Or dissolved out from wear as the metal under that chrome is not very good. Consistent with the rest of the sweat etching on the case.
A very defined line…that suggests more than random sweat ingress, I think …and given the post war need to recycle, whilst distancing oneself, from the recent past…entirely feasible I have seen other examples, of the ‘Düsseldorf’ branding with the ‘Deutsches Heer’ serial coding