This gun was so expertly made that I think it was a well known maker that didnt sign it.
I don't find the gun to be expertly made, only made to commercial standards. I have seen quite of few of these, which are almost identical. In the post Civil War era, there were many commercial supply houses which imported and sold everything required for the gun trade.....including guns. Small mercantile concerns purchased these products for sale in their own stores and often stamped their own information on the ribs. It is my
opinion that this is one of those guns.
From the 1871 Great Western Gun Works wholesale catalog:
No.114, plain iron barrels, patent breech, side by side, back action locks, oiled walnut stock, 32 to 36 inch barrels, rifle 60 to 100 balls, shot barrels 11 to 16 bore, weight 9 to 10-1/2 pounds. Price....$30.00
Similar wholesale listings are found in Folsom Bros and Homer Fisher's catalogs.