Alberto,
This is the pattern of verticle grooves you normally see on the outer edges of the toggle "knobs" of either a DWM, Erfurt, or Simson toggle.
Those grooves are missing on yours...thus my "theory" that someone may have started with a Swiss M1929 part which is also smooth along the knob edges...
Heniz has a very good point about the "gaps" in between some of the metal parts on your luger. Usually you see much tighter parts tolerances.