The .38 Detective Special is a carbon steel framed, double-action, short-barreled revolver. As the name "Detective Special" suggests, this class of gun was used as a concealed weapon by plainclothes police detectives.
The Colt Detective Special was a very popular handgun for many years. Most were chambered in .38 Special, which was considered to be a powerful round at the time, but was quickly surpassed by the .45 round. It is considered to be the first commercially successful snub-nosed revolver.
Despite its small size, the weapon is quite heavy, weighing in at 21 ounces or 595 grams.
The revolver in-game appears worn and rusty but can appear gold when the sun shines on it.
Known users of the Detective Special are Rusty Galloway, Stefan Bekowsky, and Herschel Biggs; however, most police officers of the time carried a .38 revolver of some sort. Cole Phelps' preference for the .45 is probably due to his military service.
The revolver can be used by Jack Kelso in case "House of Sticks." After Kelso escapes from the gangsters' car, if he runs any of them over, they will drop a .38 Revolver which can be used to subdue the remaining gangsters.
In the case "A Polite Invitation," Monroe's secretary used this revolver to wound Jack Kelso in the arm. Oddly, he refers to it as a "cannon" despite the fact that the .38 round was by no means the largest widely-used caliber of the time, though he may have been referring to it relative to the wielder's size.
Compared to the Colt Police Positive, the .38 is similar in stats and will kill enemies in 2-3 shots. This gun will only give the player 12 rounds until he picks up more ammo so use them wisely.