Approximately 9,000 "conversions" were manufactured c. 1871-1878 using the Richards system, patented July 25th, 1871. A small fraction of these Richards revolvers, approximately 1,200, were delivered to the U.S. Ordnance Department, and most were issued to cavalry units on the frontier, most notably the famous 10th Cavalry Regiment (Buffalo Soldiers), and nearly all saw hard use. Surviving examples of U.S. Richard's conversion Model 1860 Army revolvers are rarely seen today and inevitably show heavy service wear. This example is in well above average condition and started life as an 1863 production Colt 1860 Army percussion revolver that was subsequently converted, with "U.S." marked on the left of the barrel and a boxed script "OWA" (Orville W. Ainsworth) inspection cartouche stamped on the left of the grip. Designed by Charles Brinckerhoff Richards (1835-1919), one of the co-designers of the famous Colt Single Action Army. Richards revolvers were an important stepping stone to the Single Action Army and often saw intense use on the western frontier. They feature a breech plate with an integral notch rear sight and a floating firing pin instead of using a hammer mounted firing pin. An ejector rod housing is fitted to the right side of the barrel and the slot in the barrel lug in place of the loading lever of the percussion 1860 Army revolvers. German silver blade front sight, "-ADDRESS COL. SAML COLT NEW-YORK U.S. AMERICA-" marked on top of the barrel, "COLTS/PATENT" on the left of the frame, matching conversion number "3571" on the barrel, frame, trigger guard, back strap, loading gate, ejector rod housing and cylinder, and the original serial number "127416" visible on the barrel, trigger guard, and back strap. Provenance: The Andrew Singer Collection