The gun wouldn't pass French proof, then, or, now, in the condition you describe Geno. It would have failed the view exam at the proof house, IN ANY PROOF HOUSE, in Europe, to begin with. French proof would have torn it to pieces with .020 barrel wall thickness.
Why would you post that as evidence of anything, Geno? It would appear to be an owner altered, actually a very badly owner altered, gun.
For what it's worth, your illustration is terribly out of scale-there is a location lug that fits into the front of the watertable on a Darne, but, it has more distance from the lug at the rear than is shown.
Not sure what your point is. Unless, you are making my point for me, and showing how brutal the conditions are for sporting guns in the hands of Soviet era Russians.
Best,
Ted