Please note the Crown over D mark of Cannons Delcour on Researcher's gun; additional confirmation as to the source of the tubes used by U.S. doublegun makers

[Linked Image from photos.smugmug.com]

The mark has been found on Smith (“Crown Steel”), Fox, Meriden/Sears, Baker (“Homotensile Steel”), Ithaca NID (“Best Fluid Steel”) and Lefever Nitro Special & A-grade barrels