No, Tim. The very first Darnes were made with other companies barrels, that stamp showed up about the time they started producing their own. You don't find it on later guns-They sure put a ton of information on the barrels flats, didn't they?
It says "Cannons Frettes" and "Sans Soudure" (monobloc barrels without braze) but, I don't see a clear line where the monobloc and barrels would come together. I suppose a reblue or two could have removed that.
Sure is a neat old gun.

Best,
Ted