This eagle resembles the German Imperial eagle in use from 1871 to 1918. The imperial eagle was used, as part of their private proof, pre-1893, but also by the German state arsenals on military 98s as an acceptance stamp. But this eagle is slightly different: It lacks the imperial crown over it's head! Here is the same eagle, also on a small-ring Kar98a action:

Apparently this crownless eagle was used immediately post-WW1 by the former Government arsenals Erfurt and Danzig. After November 1918 there was no Kaiser or king anymore, so no crown over the eagle. Both arsenals tried to convert to civilian gunmaking, using Kar98a actions. The Danzig factory was renamed "Gewehrfabrik Danzig", while the Erfurt one was called "Reichswerke Erfurt" =RwE. After the Versailles so-called "Peace Treaty" 1920, both factories were dismantled by the allied disarmament comissions.
IMHO this is one of these ca 1919 rifles, but somewhat upgraded by engraving and a soldered-on rib, perhaps in-house in Erfurt or by some of the many unemployed Suhl/Zella-Mehlis craftsmen.