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Cartridges

Frenchman Louis-Nicolas Flobert invented the first rimfire metallic cartridge in 1845. His cartridge consisted of a percussion cap with a bullet attached to the top. Flobert then made what he called " parlor guns " for this cartridge, as these rifles and pistols were designed to be shot in indoor shooting-parlors in large homes. These 6mm Flobert cartridges do not contain any powder, the only propellant substance contained in the cartridge is the percussion cap. In English-speaking countries, the 6mm Flobert cartridge corresponds to.22 BB Cap and.22 CB Cap ammunition. These cartridges have a relatively low muzzle-velocity of around 700 ft/s (210 m/s).

Cartridges represented a major innovation: firearms ammunition, previously delivered as separate bullets and powder, was combined in a single metallic (usually brass) cartridge containing a percussion cap, powder, and a bullet in one weatherproof package. The main technical advantage of the brass cartridge case was the effective and reliable sealing of high-pressure gasses at the breech, as the gas pressure forces the cartridge case to expand outward, pressing it firmly against the inside of the gun-barrel chamber. This prevents the leakage of hot gas which could injure the shooter. The brass cartridge also opened the way for modern repeating arms, by uniting the bullet, gunpowder, and primer into one assembly that could be fed reliably into the breech by mechanical action in the firearm.

Before this, a "cartridge" was simply a pre-measured quantity of gunpowder together with a ball in a small cloth bag (or rolled paper cylinder), which also acted as wadding for the charge and ball. This early form of cartridge had to be rammed into the muzzleloader's barrel, and either a small charge of gunpowder in the touch hole or an external percussion cap mounted on the touch hole ignited the gunpowder in the cartridge. Cartridges with built-in percussion caps (called "primers") continue to this day to be the standard in firearms. In cartridge-firing firearms, a hammer (or a firing pin struck by the hammer) strikes the cartridge primer, which then ignites the gunpowder within. The primer charge is at the base of the cartridge, either within the rim (a "rimfire" cartridge) or in a small percussion cap embedded in the center of the base (a " centerfire " cartridge). As a rule, centerfire cartridges are more powerful than rimfire cartridges, operating at considerably higher pressures than rimfire cartridges. Centerfire cartridges are also safer, as a dropped rimfire cartridge has the potential to discharge if its rim strikes the ground with sufficient force to ignite the primer. This is practically impossible with most centerfire cartridges.

Nearly all contemporary firearms load cartridges directly into their breech. Some additionally or exclusively load from a magazine that holds multiple cartridges. A magazine is a part of the firearm which exists to store ammunition and to assist in its feeding by the action into the breech (such as through the rotation of a revolver's cylinder or by spring-loaded platforms in most pistol and rifle designs). Some magazines, such as that of most centerfire hunting rifles and all revolvers, are internal to and inseparable from the firearm, and are loaded by using a "clip". A clip (the term often mistakenly refers to a detachable "magazine") is a device that holds the ammunition by the rim of the case and is designed to assist the shooter in reloading the firearm's magazine. Examples include revolver speedloaders, the stripper clip used to aid loading rifles such as the Lee–Enfield or Mauser 98, and the en-bloc clip used in loading the M1 Garand. In this sense, "magazines" and "clips", though often used synonymously, refer to different types of devices.