In my short story, WANTED: THE SHERIFF, the hero, Sheriff Matthew Tate, carries a matched pair of 1848-Model 3 Colt Dragoons.
The Dragoon grew out of the problems with the Colt Walker revolver, a 4.5 pound, 15” long hunk of steel. The Dragoon was only 4 pounds, 2 ounces. And, where the Walker’s barrel was 9” long, the Dragoon’s was only 7.5”. The Walker was a powerful weapon, but its size meant it was used mostly as a saddle-mounted weapon. It was just too long and too heavy to wear around your waist.
And there was the propensity for the Walker to explode when users put in too much powder. Where the Walker held 60 grains of powder, the Dragoon held only 50 grains—less powder, less danger.
Also, the Walker’s loading lever tended to fall during firing, locking up the revolver and rendering the weapon useless. Not a good thing when you need a working gun. The Dragoon added a lever latch to hold it in place. Problem solved.
“Three major-production Dragoon models were produced between 1848 and 1860. The First Model had oval-shaped cylinder notches, no wheel on the rear of the hammer and no pins between the nipples. Colt produced about 7,000 First Models between 1848 and 1850. The Second Model had rectangular cylinder notches and a "wheel" on the hammer. First and Second models both had square-back trigger guards. The company made about 2,550 Second Models in 1850 and 1851. Approximately 10,000 Third Model Dragoons were made from 1851 through 1860, with many variations. All Third-Model Dragoons had a round trigger guard. Records show 8,390 Dragoons were ordered by the U.S. government.” (from http://www.cabelas.com/category/Civil-War-Colt-Dragoon/110215980.uts)
The Dragoon revolver transformed Samuel Colt's young pistol-making business into one of the most dominating forces in firearm history.