According book "Mauser military rifles of the World" it went like this:

"The cavalier on horseback is the tarditional trademark of the Pieper firm of Liege, Belgium. This particular stamp was found under the receiver of a German Gewehr 98 bearing a Crown-over-Spandau, 1916 crest. It is believed that the Imperial German national armory of Spandau suncontracted the manufacture of a number of Gew 98 receivers to both Pieper and the German industrial firm of Siemens and Halske."

So this means that yours rifle was "born" as an ordinary military mauser which later, I think between I and II WW, has rebuilt as a hunting rifle in Suhl.