Not on double rifles, but I have a Krag with a gold oval engraved "To my friend Anthony Fiala from S.A. Leonard", Mike Petrov says that S.A. was head stocker for Purdeys, a son of Daniel, was in the U.S. firm Leonard & Hyde (George Hyde designed submachine guns and did metalwork for Griffin & Howe), S.A. also did stockwork for Baker & Kimball in
Boston. Fiala was an inventor & outfitter, designed a .22 repeating pistol that looked like a Colt Woodsman, went on expeditions to the Arctic, and up the Amazon with Theodore Roosevelt, Bill Ruger told me he bought a couple of machine guns from Fiala before WWII. Petrov has a 1903 sporter signed by S.A., it has the same cheekpiece shape as my Krag. These Leonards certainly got around.