Possibly what is left of S.B.& Co which is likely Samuel Buckley & Co., thought to be a tube imported. Another,
but fluid steel, Lefever. I've never seen the mark on a Damascus barrel.
Samuel Buckley served on the Birmingham Proof House Committee and in 1863 was one of the officers in the British Small Arms Co. He later establish a branch office in Detroit. Guns produced by William Powell in the 1860s exist marked Samuel Buckley & Co., as do much later hammer guns and Anson & Deeley patent BLNEs.
See
The Double Gun Journal Vol. 22 Issue 3, 2011
The American Exporter’s Export Trade Directory of 1915 listed Samuel Buckley & Co. as “chiefly importers” with offices at 16 East 33rd St., New York, 2 Soho Square, London and Liege, Belgium.
Samuel Buckley & Co., Manhattan incorporated in July 1921.
Walt Snyder provided this quotation from Harry Howland regarding c. 1920 Ithaca Gun Co. barrels - "We were getting all our barrels forged, rough drilled and rough turned from Belgium. We were purchasing them from either Samuel Buckley & Co. or from J. Riga & Co. and it was not until two or three years later that we began purchasing those barrels from the Flannery Bolt Co."
Silvers' Super 10
Craig Havener's Flues