As proof in France was not compulsory until 1910/20 why should it have any markings ? SO if it was mad prior to compulsory proof it wont have them Its a ten bore ,end of .
Gunman,
When you see a cyanide colored Darne always remember you are looking at a post WWII gun. The process was not used pre war, and positively identifies any gun with that treatment as post WWII.
The compulsory thing about French guns is a moot point. Nobody in France would have purchased guns that were not proofed, so, they all were. Even before it was required by law.
I'd be willing to bet things would have been the same in England, had that been the case.
I promise everyone here, that if this gun had actually been a 10, it would have sold the day the add appeared. I expect the price will remain elevated for some time, guessing that the response from guys who thought they may have a line on a Darne 10 generated for Cabelas.
A ten gauge Darne is right up there with a pie bald unicorn.
Best,
Ted