Model made to fire .44 Henry Rimfire cartridge. It was to be used as a compatible companion sidearm to Henry and Winchester 1866 rifles, that were used extensively during this era. However, this was not the case; and .44 Rimfire was doomed to economic failure as soon as it appeared on the market. By that time, it had already been established that large-caliber centerfire cartridges were a good deal more efficient than their rimfire counterparts. Large-caliber rimfires were deemed obsolete before this Colt ever hit the market. The result of this was that Colt's sales representatives sold most of the production to obscure banana republics in South and Central America, where this model received much abuse. Most had original 7.5" barrels cut down; nearly all were denied even the most basic maintenance, making the survival rate of this model quite low. All this adds to its desirability as a collector's item and makes the risk of acquiring a fake that much greater. This model is unique in that it was the only SAA variation to have its own serial number range, starting with #1 and continuing to #1892, the latest known surviving specimen. Block style barrel markings were introduced during this production run. At least 90 of these revolvers were converted by the factory to .22 rimfire and one was shipped chambered for .32 rimfire.