The Colt Detective Special is a carbon steel framed double-action short-barreled revolver, a class of firearms known to gun enthusiasts as "snubnosed", "snubbies", or "belly guns". As the name "Detective Special" suggests, this class of gun was used as a concealed weapon by plainclothes police detectives. When it was introduced in 1927, the Detective Special was unlike anything on the market at the time, prior concealable revolvers were either of "break top" design and chambered for comparatively weak and low-powered cartridges, or were larger revolvers customized by shortening the barrel and grip frame. The Detective Special was the first premium grade swing-out revolver designed from the outset to be carried concealed and capable of chambering the .38 Special, a high powered cartridge in the 1920s
The Detective Special is by design a shortened and somewhat streamlined Colt Police Positive Special, sharing that revolver's slim 'D' size frame and six round capacity. It is a smaller revolver than the Official Police and the Smith & Wesson 'K' frame revolvers, such as the S&W Model 10; however, it is slightly larger than the five-shot 'J' frame Smith & Wesson revolvers that were introduced in the 1950s. During the 30's and 40's the Detective Special was one of the most popular and well respected concealable sidearms, and many were used as props in numerous Film Noir classics, as well as lesser detective dramas for television and film. It defined and evinced in many ways the quintessential concealed revolver of the period, and remains one of the few small ‘packable’ wheelguns which “offers an extra sixth round of protection”.
The Detective Special went through several issues or series. The First Series ran from the Detective Special's debut in 1927 until 1946. Compared to later issues, the First Series frame was narrower at the butt, and had less space between the butt's frontstrap and the rear of the trigger guard. Other distinctive features were a shorter ejector-rod with an ungrooved, knurled tip; a checkered hammer spur and cylinder latch, a "half-moon"-shaped front sight, and an overlapping screw and locking pin set-up on the right side of the frame. Grip panels were wooden. A rounded butt on the metal frame became standard in 1933, but pieces with the original square butt (like that of the Police Positive Special) continued to be produced into the 1940s.
The Second Series ran from 1947 to 1972. The ejector-rod was longer and had a groove in its knurled tip; a three-inch-barrel variant was offered, with a yet longer ejector-rod. The cylinder latch was smooth, and the trigger spur serrated. The right side frame screw has no locking pin, and the rear half of the front sight is a serrated ramp. The grip panels were plastic in 1947, but were changed back to wood starting in 1955 (first with a silver-tone Colt medallion, and later a gold-tone).
The transition from First to Second Series may have been more gradual than abrupt: one sees occasionally examples of post-WWII (Second Series) guns that have short ejector rods or checkered hammers. It's not clear if they left the factory this way--with the assemblers using up older parts they still had on hand--or if the apparent mis-matching was the result of subsequent repair using scrounged parts. Therefore, assigning a given revolver to a particular issue is best done by its frame's characteristics, including serial number: Colt's kept track of the serial numbers for every year the Detective Special was produced through 1978, and the serial number range for any given year is available from several sources.
In the 1960s (probably 1966), the grip frame of the Second Series Detective Special was shortened, so that the frame now matched Colt's other snub-nosed pistols (the Agent and Cobra); however, the Detective Special's grip size remained unchanged, thanks to the use of wooden grip panels that extended below the metal frame. Some shooters--especially those with large hands--found the grips uncomfortable, and resorted to a grip-spacer (like the Tyler-T adapter) to prevent the gun from hitting the middle-finger knuckle during recoil.
The Third Series ran from 1973 to 1986. A new shroud extended down from the barrel, enclosing and protecting the ejector-rod, and the front sight was changed to a full ramp. The wooden grip panels now covered the front-strap, lessening the need for a grip-spacer. The Third Series introduced an upgrade to the Detective Special's internal lockwork as well. As with the previous two Series, a few nickel-plated guns were produced; again, a 3-inch-barrel variant was offered. The decision to cease production in 1986 seems to have been, as usual, based on low sales figures, as well as the perception that--given the growing acceptance of high-capacity semi-automatic pistols among US public safety agencies and private citizens--the time for small revolvers was passed.
Colt filed for bankruptcy protection in 1992. They restarted production of the Detective Special in 1993, and while this date is often said to mark a Fourth Series, not everyone agrees. Post-1993 guns had "composite" (rubber), wrap-around grips with gold medallion. Only the two-inch barrel was offered, in blued or hard chrome finish. The Fourth Series ran only from 1993-1995, when Colt introduced its stainless-steel SF-VI (a.k.a. DS-II) to end, once and for all, the long reign of the Detective Special.
From its introduction, the Detective Special used Colt's ‘Positive Safety Lock’ (hammer block), first featured on the Police Positive; the mechanism interposes a bar between hammer and frame until the trigger is pulled, preventing accidental discharge if the hammer is struck (e.g., if a dropped gun falls onto its hammer) with the trigger forward. First and early Second Series Detective Specials are becoming highly sought after by collectors, particularly if they are in prime condition and still have the famous Colt 'Royal Blue' finish.
As mentioned above, the Detective Special was initially available in both bright blued and nickel finishes; a stainless steel finish replaced the nickeled option during the Fourth Series. For the Second Series, caliber options were .32 New Police, .38 New Police, and .38 Special; only .38 Special was offered for the other Series. The standard barrel length was 2 inches, but also a (rare) three-inch-barrel was offered during the Second and Third Series. During the Fourth Series, a model known as the "Bobbed Detective Special" with double action only lockwork and a de-spurred ("bobbed") hammer was offered. Six-round capacity and fixed sights, consisting of a front sight on the barrel and a groove machined into the surface of the frame's top strap which formed the rear, were constants for all versions