Dr Jim's chronology lists the latest damascus barrel gun as Tom Salzer's 10 gauge Ideal made in 1917.
Hunter Arms introduced 'Crown' steel with the Pigeon gun in 1893, and may have been using up damascus tubes as early as 1900. Phil Carr has posted pics of his 1901 F grade with non-matching 4 Iron 'Oxford' tubes, which should be on A and B grade hammerguns
and a 1902 F grade has that interesting lower grade Bernard pattern seen on an occasional earlier No. 1 hammerless