True French gray is actually a hardening process, with the final quench done in a solution of potassium prussiate, instead of water. There are several other ways to get a gray color that do not involve hardening, including cutting regular rust blue back with an acid. You will have to know exactly which process you have to proceed. Any of the above gun finishes are fairly delicate, and don't hold rust at bay very well. Finishes that do hold rust away are not traditional for dougle gun use. I suppose that is why we don't see a Robar option, or epoxy finishes, listed in the Galazon catalog.
I noticed in the last Galazon catalog I received the company seems to be pushing case colored guns, and the gray isn't even an option on the 12 and 16 gauges coming out next year. Maybe the gray is the color collectors look for in the future?
It likely would be simpler just to find an RBL with the finish treatment you wish.
Best,
Ted
