Well, I found a Miroku over/under double rifle in 9.3x74R for a price I couldn't resist.
She is about 20 years old, tight as a bank vault and weighs 3.3 kg. She has ejectors and a single trigger. Her action is that of a 20ga shotgun (less metal than the B25 version).

I tried her yesterday with RWS UNI classic (the only ammo I had lying around), and she produced a 4 inch 10 shot group at 50m. I hope this will improve with other ammo.

Can anybody tell me more of this rifle? It's a copy of a Browning model, but which one? What's the history behind the Browning/Miroku relationship?

Regulation is done via a wedge between the barrels

This piece of wood is screwed to the barrels to cover the space with the fore-end.

The sight: