I just noticed the cameo of the dog on the bottom of the rifle. That's pretty unusual on a rifle, in my experience. I had an 8x57JR with an engraving of a dog chasing a wild boar, and that's the only other dog I remember on a double rifle. Dale is the fortunate owner of that DR now, and he has featured it on this forum. Here is a link to the engraving on Dale's rifle.

This is altogether different. Just the dog, not engaged in hunting game appropriate to the rifle. The other game scenes are entirely appropriate to the rifle.

Dogs are common on shotguns.

One might think that the rifle was a bespoke item. It raises the suspicion the original owner specified the caliber and also wanted his hunting dog memorialized in the engraving. BUT the maker's name doesn't appear; only the importer. Does that kill the idea of it being a bespoke gun?

It was clearly made for the American market. That in itself makes the chamber a real head-scratcher.

Many riddles here! Cool, cool gun!

Curl