What comes to my mind when seeing this soft-point bullet:
The Germans set up very few secret weather stations. One was located on Spitzbergen and called Haudegen (because the head of it was named Dege). Apart from the usual military cartridges (they had machine guns) there were soft point hunting cartridges (Teilmantel), primarily for use against polar bears. In the book I read about it, no details are mentioned. Haudegen after VE day surrendered to Norwegian troops.
Could it be the soft point cartridges had this sort of clandestine headstamp? To prevent giving away the presence of Germans if someone found a fired case by accident? (as an RWS or DWM or military headstamp would have done)
This admittedly is speculation, but the nature of the soft point ammunition for these military stations has always been a riddle to me. Because the existence of Haudegen seems largely forgotten, I wanted to bring up this (remote) possibility.