Vlim - I can pin down the time when Winchester stoped calling it 7.65m/m Luger and started with the “.30 Luger.” Designation. I am not “wealthy” with 1940s Winchester catalogs, but my last catalog with the “7.65m/m” designation is the price list effective January 2, 1942 and the first one I have with the “.30 Luyger” designation is The July 9, 1946 price list. So, within the factory, the designation chaged between those years.
However, that said, the cartridge characteristics of all of my W.R.A. .30 Luger rounds are post-war. For a fairly slow-selling cartridge, they do not automatically change headstamp bunters, very expensive at that time, just to change something like that change of designation. They use them until they wear out. This would have been especially true for the WW2 years, when civilian ammunition production was largely curtailed anyway.
On that particular caliber, for example, the “WRA” headstamp was being used for years after the popular-selling calibers had been changed to the “W-W” headstamp. So, we can’t go by catalog terminology changes for more than interest and a general time frame, when discussing headstamp bunters.
Hope this is of some help and interest.