Nice little rifle. I'd guess it was probably an 8.14x46R,,not much of a job to rechamber to 32Win Sp. A lot of rifles in that nice old target and light game caliber were done over to the Winchester caliber for nothing more than ammo availability.
But as stated, the 32Sp is a handful when shot in these lightweight little pieces.
Australian Martini Cadets were sometimes rechambered to it also with the same effect on the shooter.

Is there a filled dovetail on the top of the frame?
It's outline suggests that to me.
It doesn't follow the edge of the rec'vr ring as the other frame border cut lines do.

It doesn't really detract,,the only reason I bring it up is that if it is,,it would be another reason I'd go gently on the loads for the rifle.
JMHO of course.

Nice engraving, nice wood,,love the DST's and oct bbl. What's not to like about a neat little Germanic style single shot rifle.