Charles Brinckerhoff Richards, along with William Mason was granted patents from 1871 to convert percussion revolvers into rear-loading metallic cartridge revolvers. These converted revolvers are nowadays identified as the "Richards-Mason Conversion". There were approximately 2100 Richard-Mason 1860 Army Conversions made from 1877 to 1878 in a serial number range 5800 to 7900.

This original Colt Model 1860 Richards-Mason Conversion was converted by the Colt factory from .44 percussion to the .44 Colt centerfire cartridge. The .44 Colt cartridge itself was developed by Colt in 1871 specifically for use in the .44 Colt conversions of the 1860 Army revolvers. The cartridge was used by the US military from 1871 until 1873 after which it was replaced by the 45 Colt.

This model was produced from 1877-1878. The serial number of this particular revolver is #6799. It has an 8" barrel which was made specifically for this series of revolvers at the Colt Factory.

The original Caliífornia-style "Slim Jim" holster pictured dates from 1860-65. The 1860 Army Slim Jim holster was popular with both soldiers and civilians. It is well worn and shows some repair stitching. For collectors, it is a desirable piece of equipment to accompany the 1860 Army revolver.