This variation was first researched and nicknamed the "Walker Replacement Dragoons" when identified by researcher John J. Fluck in 1956. He estimated 300 were made to replace the Walker revolvers that had failed and indicated they were made for the U.S. military using original Walker parts and reworked parts. More recent research by Dick Salzer, David Basnet, G. Maxwell Longfield, and others has changed our understanding of this model and shown that they were not replacements for broken Walkers or made from recycled or repaired Walker components as Fluck had theorized but were instead actually the first Dragoon revolvers sold to the U.S. government. In "Debunking the Fluck Myth: Colt Legends Die Hard" by Salzer for the American Society of Arms Collectors in Bulletin #95 from Spring 2007 the author states, "The obvious conclusion is that Colt, for reasons of completeness perhaps, chose to number the guns made for the second government contract in a closed, out-of-sequence series, beginning with 2001 and continuing to 3000. That left him with a gap in his civilian production between 1340 and 2000 which he subsequently filled with later production guns." He also notes that the tiny serial number numerals were stamped with the same dies as the civilian Walker revolvers, the Whitneyville Dragoons, and on the early "pre-First Model Dragoons" until the dies are presumed to have worn out around serial number 2650. These are among the rarest of the roughly 19,000 Colt Dragoon revolvers. It has the distinctive oval cylinder stops and brass square back trigger guard. "ADDRESS SAML COLT NEW-YORK CITY" is marked on the top barrel flat reading from the breech towards the muzzle. "COLT'S/PATENT/U.S." is marked on the left of the frame. The cylinder has the more common "MODEL U.S.M.R./COLT'S PATENT" marking and the classic "Ranger and Indian" scene showing the Texas Rangers in a running battle with the Comanche. Matching full or partial serial numbers in small "Walker" size numerals are on the arbor pin, cylinder, barrel, frame, trigger guard, and butt. There are some small inspection marks.