Factory letter states revolver was shipped to Spies, Kissam & Co. of New York City on February 1, 1875 in .44 RF and blue finish with type of stocks and barrel length not listed. No number on cylinder, otherwise visible serial numbers match. An estimated 7,000 Colt "Open Top" revolvers were manufactured in 1872-73. They are the ancestors of the Colt percussion and conversion revolvers and the direct predecessors of the famous Colt Single Action Army revolvers. Many of these scarce revolvers saw very hard use.