That is one interesting piece.
The peep sight is of a form I have never seen on a German gun - maybe a copy of a Lyman sight.
Also the steep pistol grip is peculiar on such an old gun.
The German name for that is "Kaiser grip", maybe after Wilhelm II - he had a crippled left arm, and that form of grip may have helped him.
But this ugly and rather impractical thing became really popular much later, say around 1960 or 1970, when the good taste for guns was going down.

Fuhrmann