Rimfire. The term “derringer” has come to refer to any small-sized handgun that is neither a revolver nor a semi/fully automatic pistol. It is not to be confused with mini-revolvers or pocket pistols, although some later derringers were manufactured with the pepperbox configuration.
The original Philadelphia Deringer was a muzzleloading percussion cap single-shot pistol introduced in 1825 by Henry Deringer. In total, approximately 15,000 Deringer pistols were manufactured. All were single barrel pistols with back-action percussion locks, typically .41 caliber with rifled bores, and walnut stocks. Barrel length varied from 1.5 to 6 in (38 to 152 mm), and the hardware was commonly a copper-nickel alloy known as “German silver“.
The term “derringer” (/ˈdɛrɪndʒər/) has become a genericized misspelling of the last name of Henry Deringer. A derringer is generally the smallest usable handgun of a given caliber, and was frequently used by women, because it is easily concealable in a purse or as a stocking gun.
Many copies of the original Philadelphia Deringer pistol were made by other gun makers worldwide, and the name was often misspelled; this misspelling soon became an alternative generic term for any pocket pistol, along with the generic phrase palm pistol, which Deringer’s competitors invented and used in their advertising. With the advent of metallic cartridges, pistols produced in the modern form are still commonly called “derringers”.
For loading a Philadelphia Deringer, one would typically fire a couple of percussion caps on the handgun, to dry out any residual moisture contained in the tube or at the base of the barrel, to prevent a subsequent misfire. One would then remove the remains of the last fired percussion cap and place the handgun on its half-cock notch, pour 15 to 25 grains (1 to 2 g) of black powder down the barrel, followed by ramming a patched lead ball down onto the powder, being very careful to leave no air gap between the patched ball and the powder, to prevent the handgun from exploding when used. (The purpose of the patch on the ball was to keep the ball firmly lodged against the powder, to avoid creating what was called a “short start” when the ball was dislodged from being firmly against the powder.)