Patented July 2, 1872, Colt employees Charles B. Richards and William Mason, combined their ideas for converting Colt's percussion revolvers to self-contained metallic cartridge, breech loading arms. Originally working with the percussion arms parts already in stock, guns were converted, however as they began to run out of the cap and ball components, the company began producing new sixguns as metal cartridge arms, rather than conversions. Although the numbers produced only amounted to a few thousand specimens (around 2,100 1860 Army models and about 3,800 1851 Navy models). El Paso's city marshal Dallas Stoudenmire packed a cut down Richards-Mason Army Colt. and John H. "Doc" Holliday packed a '51 new-made Navy model. Today's shooters enjoy the looks and handling capabilities of these conversion revolvers that combine the sleek lines of percussion revolvers with the convenience of self-contained cartridge sixguns. Due to the high cost and scarcity of originals, Cimarron's Richards-Mason conversions are ideal for Cowboy Action competitors as well as nostalgic gun buffs alike.