Definition of "Single Shot" in Firearms Terminology

H. Pieper Flobert-Warnant single-shot 32 rimfire rifle, right side close-up, and .32 rimfire ammo.
H. Pieper Flobert-Warnant single-shot 32 rimfire rifle - right side close-up, and .32 rimfire ammo. Russ Chastain

As the name implies, single shot refers to any firearm--which may be a pistol, rifle or shotgun--that has no magazine and holds a maximum of one cartridge at any given time. Once that cartridge is fired, you have to remove the spent cartridge case or shell, replace it with a new one, and close the action (and possibly cock the hammer) before you may fire the gun again. Even though single-barrel muzzleloading guns can only fire a single shot per loading, they are not usually referred to as "single shot." The term is normally reserved for use with cartridge-firing guns.

Types of single-shot actions include (but are not limited to) rolling block, falling block, tip-up, break-open, bolt action, Flobert, Martini, and trapdoor. 

Single-shot firearms were the natural result of firearms development. At the time when the metallic cartridge was invented and made practical, firearms were of the muzzleloading type. It only made sense to convert some of those guns into cartridge guns in the simplest possible manner, and to use existing factory machinery and gun parts to make simple, easy-to-build guns. Both of those scenarios resulted in single-shot firearms.

It wasn't too many years before the advent of guns with attached magazines or rotating cylinders rendered the single-shot concept obsolete for most guns, but it has held on over the years. In some cases, such as break-open shotguns, it is often a matter of affordability--single-shot firearms are often cheap. Sometimes it's just a matter of liking the looks of an old-fashioned gun.

Other hunters like the challenge of trying to make a kill with only one shot when hunting—a somewhat questionable preference, as ethical hunters want to follow up a shot quickly in the event that the first shot does not kill.  And some single-shot rifles and pistols are far more costly than a good bolt-action repeater, which is another argument in favor of hunting with repeating firearms.

But single-shot firearms will always have a place in some shooters' hearts, and that's as it should be.