The scope bases are old and would surprise me if they don't date to somewhere between the wars. My guess is that the scope was mounted sans see-through bases in a low position and had to have the bases reversed from what we normally see for configuration to be removable.

I have a Hensoldt Klein Dialyt straight tube 2 3/4x scope that I intend to put on the rifle and in a low mount position it appears that the action may have to be opened to remove such a scope.

Dennis