Thanks Tmine! Nice to see how Swedish looks like a mix of Germenglish with some Dutch ;-). I did some further searching and I think I figured it out by combining some references.
On reference
http://en.wikipedia.org/wiki/Orzeł_class_submarine it is stated that Holland made submarines for Poland (Orzel class) just before WW2, and installed the 10,5 cm M/25 Bofors (the Polish sank 1 of our subs by accident.....). The Dutch themselves installed 8,8 cm Bofors guns on their submarines, so Bofors would be a sensible choice. More info on the armament of both on
www.dutchsubmarines.com. My case is dated after 1940 so I can assume it is made by Sweden, for Sweden. The Swedish used the 10,5 cm M/25 on the Draken class submarines.
When looking for information I also found that Sweden had a 10,5 cm L/41 gun on their Arholma class minesweeper (12 pieces). reference
http://www.navypedia.org/ships/sweden/sw_ms_arholma.htm. This type of gun is also seen on
http://www.navweaps.com/Weapons/WNSweden_41-41_m1936.htm as both a 10,5 cm M/36 for Poland (Orzel class sub again!) and the 10,5 cm M/40 for Swedish Arholma class. So it seems the M/25 was renamed making it so hard to find any info. To finalize my case has a stamp that could well be interpreted as "10,5 cm M/40" meaning it was indeed made for the gun as installed on the Swedish Arholma class minesweeper.
Now that I think I have found the gun used for this case, I am interested in other headstamps for the 105x544R Bofors case.
Also, I still do not know the meaning of the typical Swedish "NJ" fishhook like logo. I have this logo on this case, a 37 mm AT case WW2 and a undated 25 mm Bofors case. I really would like to know the meaning and if it is used post-war or not (to date my 25 mm case).
Pictures from left to right:
- headstamp of my 10,5 cm M/40 Bofors case
- detail of headstamp showing 10,5 cm M/40 and unknown NJ logo
- Swedish 10,5 cm M/40 gun
- my 10,5 cm M/40 shell case
- Polish 10,5 cm M/25 M/36 Bofors deck gun on Orzel class submarine