The main reason the Colt 1873 came to be is because Colt wanted the US Army's contract for cartridge revolvers. They had submitted the Open Top to the Army, S&W and Remington submitted their candidates too. The army came back and told Colt they had rejected their pistol because it has no top strap. Colt hurriedly redesigned their gun with a top strap, resubmitted it to the Army for evaluation and the rest is history. S&W got somewhat of a consultation prize when they were a few years later awarded a small contract for the Schofield revolver and Remington lost out.