More pictures would help, though this pattern long ago was solved by CB and Joe Steen 2008-09; Spandau cut G98 production loose in early 1917 to concentrate on MG production; receivers left in the pipeline (none Spandau made, but subcontracted from Peiper-S&H were increasing diverted to others, among which included the G98 king - DZ or Danzig - the right receiver, if you show it will reveal Danzigs acceptance pattern. Obviously this rifle passed through Spain's nasty war between conservatism (nationalist factions, with some bad guys) and far left, ( and separatists groups, Liberals and increasing dominated by Red communists)
Anyway you do not show enough to be very specific beyond a general outline of the variant (DZ context and barrel implications); more could be said if serial & right receiver were shown, specifically where it falls in general production prior to the 1918 & SCW.
