they might be original - the form makes sense when a scope is mounted. I have never seen such either.

But then a lot of work has been done on that gun:
- brand-new Zeiss scope
- the Kahles scope might be from the 1970s
- rifle barrels might be quite new and sleeved, funny caliber combination 6x52R and .22 Hornet
- if one barrel really is 6x52R (the Bretschneider cartridge) then this was done quite recently http://www.bretschneider-waffen-munition.de/Geschichte/geschichte.html
- what about the other barrel pair, shotgun barrels 32 gauge? But why the rear sight?

fuhrmann