Peelen - my research indicated to me that the four-star headstamp virtually always found in the Gustloff boxes was one from their stewardship of the company at Hirtenberg. The Austrian headstamp that predated it was H l * l * l * l. Perhaps someone on your side of the Atlantic could confirm that if they have any earlier style box, when it still was a Mandl company, with the four-star headstamped ammunition in it. I was never able to find any such confirmation.
Lew - the rim thickness on a 9 mm Browning Long cartridge is approximately the same as that of most 9 mm Parabellum rounds, as well as many other auto pistol calibers. It is not apprecialy thinner, if at all.
Although not officially adopted by Belgium, the Model 1903 FN-Browning pistol was in some use in that country, as well as Russia and Estonia, the Netherlands, Sweden and the Ottoman Emire (Turkey) There was also the Le Français pistol of the same caliber, in France, and two Webley versions in England and South Africa. It was used in South America as well, by Paraguay and El Salvador. It would appear that the first production of this caliber by Gustloff Werke Hirtenberg was likely for one, or both, of the South American countries, as boxes with German-language labels are actually over-labels on boxes originally using the Spanish Language, and not the reverse. I think the German-language version shows up in many places, not just Sweden. It is possible that the Gustloff ammunition was sent to Sweden, but in truth, Norma was making this caliber in Sweden, and Ammunitionsfabriken Marieberg, at Stockholm, made this caliber off and on between 1910 and 1942. This makes me wonder why Sweden would need any ammunition of this caliber. Ammunition from Norma with the 027 code was made as late as 1973, although in cases dated “72” and a Finnish box for ammunition of 027 manufacture shows a lot number dating from 1982, even though once again, the cartridge cases are dated “72.”
I suspect that the Gustloff rounds in the German labeled boxes, still showing the headstamp * * * * may have simply been made for the various pistols captured by the German military forces during the course of the war. I could be wrong, of course, since I was never able to find any documentation concerning where they went. Regardless, since over-labeled, they seemed to be nothing more than a cleanup of the rounds originally made for one the the Spanish-speaking countries. Of course in WWI, Germany had enough need for the 9 mm Browning Long cartridge that they produced it, in military-style 16 round boxes, at Rheinische Metallwaaren- und Maschinenfabrik, Düsseldorf in the months of May thru October 1918.
Just my view on this. Very little real documentation on this subject.