Q: When my father retired in 1967, he gave me a Colt revolver. It is stamped “COLT D.A. 38” and has a serial number in two adjacent places: the trigger guard next to the screw and the frame next to the trigger guard: 138XXX or 136XXX. I was told that Billy the Kid carried a Colt double-action revolver. Do you know if that is true?
A: From the good description you provide, we can determine that your revolver is the Colt Model 1877 Lightning chambered in .38 Long Colt.
It is a double-action model as stated on the barrel “COLT D.A. 38.” This means you can fire the gun by first cocking it and then pulling the trigger or just by pulling the trigger (without cocking the hammer by hand). In other words, you could pull the trigger six times and empty the gun.
Many sources indicate that Billy the Kid sometimes carried the Colt .44 single-action gun (as seen in most cowboy movies), but he sometimes carried the Colt Thunderer D.A. .41—the big brother of your Lightning.