A high percentage of the French doubles I have seen have Belgian proofs. I suspect that Belgium was the Birmingham for many French sellers. That said, I have seen Gastine Rennet [can never get the spelling of that right] guns that are second to none. These often have Belgian proofs. A three barreled 16 ga by Morian is another example. Paris address, Belgian proofs.

http://www.bakercollectors.com/