Tom thanks for posting the pictures and the letter. I believe this gun was made in 1889 and could have been one of the last ones made in Syracuse but not serial numbered in Syracuse or the Hunter Bros. told Syracuse to start the serial numbers at 30,000 of their last inventory of guns and parts.
It seems kind of odd that if Fulton did serial number these early guns how come they could not put a their name on the barrels!
This gun is a Syracuse gun, no doubt, has the large breech balls and is a Quality 3. I also believe the records were lost for these early guns in the later part of 1889.

Tom does this gun have the hour-glass ebony for-end?