With all those Helice guns, looks like V-C specialized in the engraved keys. My 1922 catalog is a reproduction with somewhat fuzzy images. But even in many of those you can make out engraving on the key and top lever.

That catalog is worth the price if for nothing more than the full page photo of French WWI ace of aces Rene Fonck and his recommendation for the V-C Helice Grip: "The game birds fall like Krauts!"