I'd agree with the others, I imagine Chevillard put his name on the gun and sold it but it was made elsewhere.

My little Seytre game gun, has "Lacroix Paris" on the rib, and that was the owner of a other dodgy shop in the 1950s-60s. He just put his name on the gun. Seems my little baby was originally a Belgian action that was sent to a M. Seytre in Saint Etienne in the 1950s and finished. It was then sold in M. Lacroix's shop.