Answer and gun photo provided by firearms expert

Keith Mueller  

Though the revolver makes only a few appearances, I can tell you it is definitely a Colt. Based upon the barrel configuration with the flat front to the underbarrel lug and the raised vented rib atop the barrel and the shape of the hammer, it was either a Colt Python .357 Magnum (the Python I believe was issue in the SF Police Department at the time) with 2 1/2 inch barrel or a Colt Diamondback .38 Special also with a 2 1/2" barrel. My vote would go for the Diamondback for one simple reason. About the only part of the gun we really get a good look at is the butt of the holstered revolver once when Mr. McQueen puts the gun on in his apartment, and especially in the last shot of the film where the gun is shown briefly in close-up, again holstered. The grip configuration is a standard Colt design that was a round butt shaped walnut grip that was actually manufactured for the Colt Detective Special revolver. Both the Detective Special and the Diamondback shared the same frame. The difference being the barrel and hammer of the Diamondback were made to look like that of the popular Python and the addition of adjustable sights which the Detective Special did not have. The factory grip for the short-barreled Diamondback was a slightly smaller version of the factory grip for the short Python; it flared toward the bottom and had a very flat, angular shape which would make it less easy to conceal under clothing. It would be a simple matter to put the round butt Detective Special grip on the Diamondback to facilitate concealment. This round butt style grip was never available from Colt for the larger Python. As the grip is obviously a standard Colt pattern, the gun has to be a Diamondback! And high marks to the producers of the film who thought of the fine touch of making the gun more concealable; clearly the mark of a gun savvy individual!

 The top gun is the Python. Note the flairing grip with the very flat bottom and sharp edges. Below this is the Diamondback. The factory issue grips for the Diamondback are slightly smaller versions of those for the Python. On this gun I have put on the rounded Detective Special grips like the ones on the gun in Bullitt. The bottom gun is the Detective Special that every TV and movie cop and bad guy carried in the 1940's and 1950's. You can see that the factory grips on this gun are the rounded style like I have on the Diamondback. Colt never made this style of grip for the Python.

The Colt Diamondback is a very reliable gun; the "chassis" so to speak is a design that was begun in the late 19th century and improved upon over the years. The basic design saw many years of service with police departments here and abroad. The nice thing about the Diamondback is that it is a small revolver with decent sights! Most of the snubbie guns of that era tend to have very thin front sights and small notches in the back of the frame for the rear sight. The Diamondback gives one all the advantages of a small revolver with the "big gun" advantage of sights you can actually see! Also, for the time, Colt was the only company that made a small snub nose gun that held six rounds; the S & W Chief's Special models were only slightly smaller, but only held five rounds.