Raimey,

This is an interesting gun. I think you are right it is a Facile Princips knockoff. With that design the action cocks as the result of levers articulating on the front barrel lump. I believe part of the mechanism is visible in the top photo. I also note the absence of cocking levers or rods protruding through the front of the bars. However, being a Facile Princips variant wouldn't make the action fat or pregnant looking.

So then I notice the mechanics in the action face just above and behind the rear lump. What is all that?

I also wonder about the extractor or ejector mechanism. There's unfamiliar hardware nestled in the barrel lumps.

Pardon my ignorance. Can anyone shed light on these mysteries?

Very interesting, indeed. Thanks,
Curl