Apparently no-one except the Swedes stamped the crown.
If you'll do a little more research you'll find this is far from the truth.
I did open the page you linked and it's nothing but google pictures. If you'll bother to go to the actual website from the picture there is a lot info on it about the date marks and the 1920 marks above the original date. What you won't find is any mention of it being a Swedish rifle.
From the page you posted a link to:
1920 is not actually a date "per se". "1920" is the ownership stamp of the Weimar Republic. It was added to all former Imperial arms set aside under the strict limitations of the Versailles Treaty for use by the severely limited post-war German Armed Forces.
1920 refers to the year the weapons program came into effect after the bickering and in-fighting amongst the allies in 1919 to determine how severely to hamstring the new German gov't. Of course, we all know they went to far and basically set europe up for the next war 20-odd years later. hindsight is, after all, 20/20.Was Sweden bound by the Versailles Treaty? I don't think so.
Do the majority if not all of the Erfurt Kar98's have the crown crest? Yes, they do.
Here is the google picture page you tried to link.
google pictures Here is the actual page the picture you are going by is from:
The explanation of the picture you saw. If you'll bother to read the actual page it will give you a lot of useful information.
