Cartridge (firearms)
A cartridge or a round is a type of pre-assembled firearm ammunition packaging a projectile (bullet, shot, or slug), a propellant substance (usually either smokeless powder or black powder) and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for the practical purpose of convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often informally used to refer to a complete cartridge, it is correctly used only to refer to the projectile. Cartridges can be categorized  by the type of their primers – a small charge of an impact- or electric-sensitive chemical mixture that is located: at the center of the case head (centerfire); inside the rim (rimfire); inside the walls on the fold of the case base that is shaped like a cup (cupfire, now obsolete); in a sideways projection that is shaped like a pin (pinfire, now obsolete); or a lip (lipfire, now obsolete); or in a small nipple-like bulge at the case base (teat-fire, now obsolete). Only the centerfire and rimfire survived mainstream usage today. Military and commercial producers continue to  pursue the goal of caseless ammunition. Some artillery ammunition uses the same cartridge concept as found in small arms. In other cases, the artillery shell is separate from the propellant charge. A cartridge without a projectile is called a "blank"; one that is completely inert (contains no active primer and no propellant) is called a "dummy"; one that failed to ignite and shoot off the projectile is called a "dud"; and one that ignited but failed to sufficiently push the projectile out of the barrel is called a "squib". Design. Purpose. The cartridge was invented specifically for breechloading firearms. Prior  to its invention, the projectiles and propellant are carried separately and had to be individually loaded via the muzzle into the gun barrel before firing, then have a separate ignitor compound (from a slow match, a small charge of gunpowder in a flash pan, or a percussion cap) to set off the shot. Such loading procedures often necessitates adding paper/cloth wadding and ramming down repeatedly with a rod to optimize the gas seal, and are thus clumsy and inconvenient, severely restricting the practical rate of fire of the weapon, as well as complicating the logistics of ammunition. The primary  purpose of a cartridge is to offer a handy pre-assembled "all-in-one" package that is convenient to handle and transport, easily inserted into the breech (rear end) of the barrel, as well as preventing potential propellant loss, contamination or degradation from moisture and the elements. In modern self-loading firearms, the round also enables the action mechanism to use part of the propellant energy (carried by the cartridge itself) and cyclically load new rounds of ammunition to allow quick repeated firing. To perform a firing, the round is first inserted into a "ready" position within the chamber aligned  with the bore axis (i.e. "in "battery""). While in the chamber, the cartridge case obturates all other directions except the bore to the front, reinforced by a breechblock or a locked bolt from behind, designating the forward direction as the path of least resistance. When the trigger is pulled, the sear disengages and releases the hammer/striker, causing the firing pin to impact the primer embedded in the base of the cartridge. The shock-sensitive chemical in the primer then creates a jet of sparks that travels into the case and ignites the main propellant charge within, causing the powders  to "deflagrate" (but not "detonate"). This rapid exothermic combustion yields a mixture of highly energetic gases and generates a very high pressure inside the case, often fire-forming it against the chamber wall. When the pressure builds up sufficiently to overcome the fastening friction between the projectile (e.g. bullet) and the case neck, the projectile will detach from the case and, pushed by the expanding high-pressure gases behind it, move down the bore and out the muzzle at extremely high speed. After the bullet exits the barrel, the gases are released to the surrounding as ejectae and the chamber  pressure drops back down to atmospheric level. The case, which had been elastically expanded by high pressure, contracts slightly, which eases its removal from the chamber when pulled by the extractor. The spent cartridge, with its projectile and propellant gone but the case still containing a used-up primer, then gets ejected from the gun to clear room for a subsequent new round. Components. A typical modern cartridge consists of four components: the case, the projectile, the propellant, and the primer. Case. The main defining component of the cartridge is the case, which gives the cartridge its shape and serves  as the integrating housing for other functional components – it acts as a container for the propellant powders and also serve as a protective shell against the elements; it attaches the projectile either at the front end of the cartridge (bullets for pistols, submachine guns, rifles, and machine guns) or inside of the cartridge (wadding/sabot containing either a number of shot or an individual slug for shotguns), and align it with the barrel bore to the front; it holds the primer at the back end, which receives impact from a firing pin and is responsible for igniting the main propellant  charge inside the case. While historically paper had been used in the earliest cartridges, almost all modern cartridges use metallic casing. The modern metallic case can either be a "bottleneck" one, whose frontal portion near the end opening (known as the "case "neck"") has a noticeably reduced diameter than the main part of the case ("case "body""), with a noticeably angled slope ("case "shoulder"") in between; or a "straight-walled" one, where there is no narrowed neck and the whole case looks cylindrical. The case shape is meant to match exactly to the chamber of the gun that fires it , and the "neck", "shoulder" and "body" of a bottleneck cartridge have corresponding counterparts in the chamber known as the "chamber neck", "chamber shoulder" and "chamber body". The front opening of the case neck, which receives and fastens the bullet via crimping, is known as the "case mouth". The closed-off rear end of the case body, which holds the primer and technically is the case "base", is ironically called the "case head" as it is the most prominent and frequently the widest part of the case. There is a circumferential flange at the case head called a "rim", which provides  a lip for the extractor to engage. Depending on whether and how the rim protrudes beyond the maximum case body diameter, the case can be classified as either "rimmed", "semi-rimmed", "rimless", "rebated" or "belted". The shape of a bottleneck cartridge case (e.g. body diameter, shoulder slant angle and position, neck length) also affects the pressure generable inside the case, which in turn influences the accelerative capacity of the projectile. Wildcat cartridges are often made by reshaping the case of an existing cartridge. In addition to case shape, rifle cartridges can also be grouped according to the case dimensions, which  in turn dictates the minimal receiver size and operating space (bolt travel) needed by the action, into either "mini-action", "short-action", "long-action" or "magnum" categories. The most popular material used to make cartridge cases is brass due to its good corrosion resistance. The head of a brass case can be work-hardened to withstand the high pressures, and allow for manipulation via extraction and ejection without rupturing. The neck and body portion of a brass case is easily annealed to make the case ductile enough to allow reshaping so that it can be reloaded many times, and fire  forming can help accurize the shooting. Steel casing is used in some plinking ammunition, as well as in some military ammunition (mainly from the former Soviet Union and China). Steel is less expensive to make than brass, but it is far less corrosion-resistant and not feasible to reuse and reload. Military forces typically consider service small arms cartridge cases to be disposable, single-use devices. However, the mass of the cartridges can affect how much ammunition a soldier can carry, so the lighter steel cases do have a logistic advantage. Conversely, steel is more susceptible to contamination and damage  so all such cases are varnished or otherwise sealed against the elements. One downside caused by the increased strength of steel in the neck of these cases (compared to the annealed neck of a brass case) is that propellant gas can blow back past the neck and leak into the chamber. Constituents of these gases condense on the (relatively cold) chamber wall, and this solid propellant residue can make extraction of fired cases difficult. This is less of a problem for small arms of the former Warsaw Pact nations, which were designed with much looser chamber tolerances than NATO weapons . Aluminum-cased cartridges are available commercially. These are generally not reloaded, as aluminum fatigues easily during firing and resizing. Some calibers also have non-standard primer sizes to discourage reloaders from attempting to reuse these cases. Plastic cases are commonly used in shotgun shells, and some manufacturers have now started offering polymer-cased centerfire rifle cartridges. Projectile. As firearms are projectile weapons, the projectile is the effector component of the cartridge, and is actually responsible for reaching, impacting and exerting damage onto a target. The word "projectile" is an umbrella term that describes any type of kinetic objects launched into  ballistic flight, but due to the ubiquity of rifled firearms shooting bullets, the term has become somewhat a technical synonym for bullets among the handloading crowds. The projectile's motion in flight is known as its external ballistics; and its behavior upon impacting an object is known as its terminal ballistics. A bullet can be made of virtually anything (see below), but lead is the traditional material of choice because of its high density, malleability, ductility and low cost of production. However, at speeds of greater than , pure lead will deposit fouling in rifled bores at an ever-increasing rate . Alloying the lead with a small percentage of tin and/or antimony can reduce such fouling, but grows less effective as velocities are increased. A cup made of harder metal (e.g. copper), called a gas check, is often placed at the base of a lead bullet to decrease lead deposits by protecting the rear of the bullet against melting when fired at higher pressures, but this too does not work at higher velocities. A modern solution is to cover bare lead in a protective powder coat, as seen in some rimfire ammunitions. Another solution is to encase a lead core within  a thin exterior layer of harder metal (e.g. gilding metal, cupronickel, copper alloys or steel), known as a "jacketing". In modern days, steel, bismuth, tungsten and other exotic alloys are sometimes used to replace lead and prevent release of toxicity into the environment. In armor-piercing bullets, very hard and high-density materials such as hardened steel, tungsten, tungsten carbide, or even depleted uranium are used for the penetrator core. Non-lethal projectiles with very limited penetrative and stopping powers are sometimes used in riot control or training situations, where killing or severely wounding a target would be undesirable. Such  projectiles are usually made from softer and lower density materials, such as plastic or rubber bullets. Wax bullets are occasionally used for force-on-force tactical trainings, and pistol dueling with wax bullets used to be a competitive Olympic sport prior to the First World War. For smoothbore weapons such as shotguns, small metallic balls known as shots are typically used, which is usually contained inside a semi-flexible, cup-like sabot called "wadding". When fired, the wadding is launched from the gun as a payload-carrying projectile, loosens and opens itself up after exiting the barrel, and then inertially  releases the contained shots as a hail of sub-projectiles. Shotgun shots are usually made from bare lead, though copper/zinc–coated steel balls (such as those used by BB guns) can also be used. Lead pollution of wetlands has led to the BASC and other organisations campaigning for the phasing out of traditional lead shot. There are also unconventional projectile fillings such as bundled flechettes, rubber balls, rock salt and magnesium shards, as well as non-lethal specialty projectiles such as rubber slugs and bean bag rounds. Solid projectiles (e.g. slugs, baton rounds, etc.) are also shot while contained  within a wadding, as the wadding obturates the bore better and typically slides less frictionally within the barrel. Propellant. The propellant is what actually fuels the main function of any firearm (i.e. shooting out the projectile). When a propellant deflagrates (subsonic combustion), the redox reaction breaks its molecular bonds and releases the chemical energy stored within. At the same time, the combustion yields significant amount of gaseous products, which is highly energetic due to the exothermic nature of the reaction. These combustion gases become highly pressurized when confined in a rigid space – such as the cartridge casing (reinforced by the  chamber wall) occluded from the front by the projectile (bullet, or wadding containing shots/slug) and from behind by the primer (supported by the bolt/breechblock). When the pressure builds up high enough to overcome the crimp friction between the projectile and the case, the projectile separates from the case and gets "propelled" down the gun barrel by further expansion of the gases like a piston engine, receiving kinetic energy from the propellant gases and accelerating to a very high muzzle velocity within a short distance (i.e. the barrel length). The projectile motion driven by the propellant inside the gun  is known as the internal ballistics. The oldest gun propellant was black gunpowder, a low explosive made from a mixture of sulfur, carbon and potassium nitrate, invented in China during the 9th century as one of Four Great Inventions, and still remains in occasional use as a solid propellant (mostly for antique firearms and pyrotechnics). Modern firearm propellants however are smokeless powders based on nitrocellulose and nitroglycerin, first invented during the late 19th century as a cleaner and better-performing replacement of the black powder. Modern smokeless powder may be corned into small spherical balls, or extruded into cylinders or  strips with many cross-sectional shapes using solvents such as ether, which can be cut into short ("flakes") or long pieces ("cords"). The performance characteristics of a propellant are greatly influenced by its grain size and shape, because the specific surface area influences the burn rate, which in turn influences the rate of pressurization. Short-barrel firearms such as handguns necessitates faster-burning propellants to obtain sufficient muzzle energy, while long guns typically use slower-burning propellants. Due to the relatively short distance a gun barrel can offer, the sealed acceleration time is very limited and only a small proportion  of the total energy generated by the propellant combustion will get transferred to the projectile. The residual energy in the propellant gases gets dissipated to the surrounding in the form of heat, vibration/deformation, light (in the form of muzzle flash) and a prominent muzzle blast (which is responsible for the loud sound/concussive shock perceivable to bystanders and most of the recoil felt by the shooter, as well as potentially deflecting the bullet), or as unusable kinetic energy transferred to other ejecta byproducts (e.g. unburnt powders, dislodged foulings). Primer. Because the main propellant charge are located deep inside the  gun barrel and thus impractical to be directly lighted from the outside, an intermediate is needed to relay the ignition. In the earliest black powder muzzleloaders, a fuse was used to direct a small flame through a touch hole into the barrel, which was slow and subjected to disturbance from environmental conditions. The next evolution was to have a small separate charge of finer gunpowder poured into a flash pan, where it could start a "priming" ignition by an external source such as a slow match (matchlock), or a pyrite (wheellock) or a flint striking a steel frizzen (snaplock and  flintlock) to create sparks. When the primer powder starts combusting, the flame is transferred through an internal touch hole called a "flash hole" to provide activation energy for the main powder charge in the barrel. The disadvantage was that the flash pan could still be exposed to the outside, making it difficult (or even impossible) to fire the gun in rainy or humid conditions as wet gunpowder burns poorly. After Edward Charles Howard discovered fulminates in 1800 and the patent by Reverend Alexander John Forsyth expired in 1807, Joseph Manton invented the precursor percussion cap in 1814, which was further  developed in 1822 by the English-born American artist Joshua Shaw, and caplock fowling pieces appeared in Regency era England. These guns used a spring-loaded hammer to strike a percussion cap placed over a conical "nipple", which served as both an "anvil" against the hammer strike and a transfer port for the sparks created by impactfully crushing the cap, and was easier and quicker to load, more resilient to weather conditions, and more reliable than the preceding flintlocks. Modern primers are basically improved percussion caps with shock-sensitive chemicals (e.g. lead styphnate) enclosed in a small button-shaped capsule . In the early paper cartridges, invented not long after the percussion cap, the primer was located deep inside the cartridge just behind the bullet, requiring a very thin and elongated firing pin to pierce the paper casing. Such guns were known as needle guns, the most famous of which was decisive in the Prussian victory over the Austrians at Königgrätz in 1866. After the metallic cartridge was invented, the primer was relocated backwards to base of the case, either at the center of the case head (centerfire), inside the rim (rimfire, inside a cup-like concavity of the case base  (cupfire), in a pin-shaped sideways projection (pinfire), in a lip-like flange (lipfire), or in a small nipple-like bulge at the case base (teat-fire). Today, only the centerfire and rimfire have survived the test of time as the mainstream primer designs, while the pinfire also still exists but only in rare novelty miniature guns and a few very small blank cartridges designed as noisemakers. In rimfire ammunitions, the primer compound is moulded integrally into the interior of the protruding case rim, which is crushed between the firing pin and the edge of the barrel breech (serving as  the "anvil"). These ammunitions are thus not reloadable, and are usually on the lower end of the power spectrum, although due to the low manufacturing cost some of them (e.g. .22 Long Rifle) are among the most popular and prolific ammunitions currently being used. Centerfire primers are a separately manufactured component, seated into a central recess at the case base known as the "primer pocket", and have two types: Berdan and Boxer. Berdan primers, patent by American inventor Hiram Berdan in 1866, are a simple capsule, and the corresponding case has two small flash holes with a bulged bar in  between, which serves as the "anvil" for the primer. Boxer primers, patented by Royal Artillery colonel Edward Mounier Boxer also in 1866, are more complex and have an internal tripedal "anvil" built into the primer itself, and the corresponding case has only a single large central flash hole. Commercially, Boxer primers dominate the handloader market due to the ease of depriming and the ability to transfer sparks more efficiently. Due to their small size and charge load, primers lack the power to shoot out the projectile by themselves, but can still put out enough energy to separate the bullet from  the casing and push it partway into the barrel – a dangerous condition called a squib load. Firing a fresh cartridge behind a squib load obstructing the barrel will generate dangerously high pressure, leading to a catastrophic failure and potentially causing severe injuries when the gun blows apart in the shooter's hands. Actor Brandon Lee's infamous accidental death in 1993 was believed to be caused by an undetected squib that was dislodged and shot out by a blank. Manufacturing. To manufacture cases for cartridges, a sheet of brass is punched into disks. These disks go through a series of  drawing dies. The disks are annealed and washed before moving to the next series of dies. The brass needs to be annealed to remove the work-hardening in the material and make the brass malleable again ready for the next series of dies. Manufacturing bullet jackets is similar to making brass cases: there is a series of drawing steps with annealing and washing. Specifications. Critical cartridge specifications include neck size, bullet weight and caliber, maximum pressure, headspace, overall length, case body diameter and taper, shoulder design, rim type, etc. Generally, every characteristic of a specific cartridge type is tightly controlled  and few types are interchangeable in any way. Exceptions do exist but generally, these are only where a shorter cylindrical rimmed cartridge can be used in a longer chamber, (e.g., .22 Short in .22 Long Rifle chamber, and .38 Special in a .357 Magnum chamber). Centerfire primer type (Boxer or Berdan, see below) is interchangeable, although not in the same case. Deviation in any of these specifications can result in firearm damage and, in some instances, injury or death. Similarly, use of the wrong type of cartridge in any given gun can damage the gun, or cause bodily injury. Cartridge  specifications are determined by several standards organizations, including SAAMI in the United States, and C.I.P. in many European states. NATO also performs its own tests for military cartridges for its member nations; due to differences in testing methods, NATO cartridges (headstamped with the NATO cross) may present an unsafe combination when loaded into a weapon chambered for a cartridge certified by one of the other testing bodies. Bullet diameter is measured either as a fraction of an inch (usually in 1/100 or in 1/1000) or in millimeters. Cartridge case length can also be designated in inches or millimeters. History. Paper  cartridges have been in use for centuries, with a number of sources dating their usage as far back as the late 14th and early 15th century. Historians note their use by soldiers of Christian I, Elector of Saxony and his son in the late 16th century, while the Dresden Armoury has evidence dating their use to 1591. Capo Bianco wrote in 1597 that paper cartridges had long been in use by Neapolitan soldiers. Their use became widespread by the 17th century. The 1586 round consisted of a charge of powder and a bullet in a paper cartridge. Thick paper is  still known as "cartridge paper" from its use in these cartridges. Another source states the cartridge appeared in 1590. King Gustavus Adolphus of Sweden had his troops use cartridges in the 1600s. The paper formed a cylinder with twisted ends; the ball was at one end, and the measured powder filled the rest. This cartridge was used with muzzle-loading military firearms, probably more often than for sporting shooting, the base of the cartridge being ripped or bitten off by the soldier, the powder poured into the barrel, and the paper and bullet rammed down the barrel. In the Civil  War era cartridge, the paper was supposed to be discarded, but soldiers often used it as a wad. To ignite the charge an additional step was required where a finer-grained powder called priming powder was poured into the pan of the gun to be ignited by the firing mechanism. The evolving nature of warfare required a firearm that could load and fire more rapidly, resulting in the flintlock musket (and later the Baker rifle), in which the pan was covered by furrowed steel. This was struck by the flint and fired the gun. In the course of loading a  pinch of powder from the cartridge would be placed into the pan as priming, before the rest of the cartridge was rammed down the barrel, providing charge and wadding. Later developments rendered this method of priming unnecessary, as, in loading, a portion of the charge of powder passed from the barrel through the vent into the pan, where it was held by the cover and hammer. The next important advance in the method of ignition was the introduction of the copper percussion cap. This was only generally applied to the British military musket (the Brown Bess) in 1842, a quarter  of a century after the invention of percussion powder and after an elaborate government test at Woolwich in 1834. The invention that made the percussion cap possible was patented by the Rev. A. J. Forsyth in 1807 and consisted of priming with a fulminating powder made of potassium chlorate, sulfur, and charcoal, which ignited by concussion. This invention was gradually developed, and used, first in a steel cap, and then in a copper cap, by various gunmakers and private individuals before coming into general military use nearly thirty years later. The alteration of the military flint-lock to the percussion  musket was easily accomplished by replacing the powder pan with a perforated nipple and by replacing the cock or hammer that held the flint with a smaller hammer that had a hollow to fit on the nipple when released by the trigger. The shooter placed a percussion cap (now made of three parts of potassium chlorate, two of fulminate of mercury and powdered glass) on the nipple. The detonating cap thus invented and adopted brought about the invention of the modern cartridge case, and rendered possible the general adoption of the breech-loading principle for all varieties of rifles, shotguns  and pistols. This greatly streamlined the reloading procedure and paved the way for semi- and full-automatic firearms. However, this big leap forward came at a price: it introduced an extra component into each round – the cartridge case – which had to be removed before the gun could be reloaded. While a flintlock, for example, is immediately ready to reload once it has been fired, adopting brass cartridge cases brought in the problems of extraction and ejection. The mechanism of a modern gun must not only load and fire the piece but also provide a method of removing the spent case , which might require just as many added moving parts. Many malfunctions occur during this process, either through a failure to extract a case properly from the chamber or by allowing the extracted case to jam the action. Nineteenth-century inventors were reluctant to accept this added complication and experimented with a variety of caseless or self-consuming cartridges before finally accepting that the advantages of brass cases far outweighed this one drawback. Integrated cartridges. The first integrated cartridge was developed in Paris in 1808 by the Swiss gunsmith Jean Samuel Pauly in association with French gunsmith François Prélat. Pauly created  the first fully self-contained cartridges: the cartridges incorporated a copper base with integrated mercury fulminate primer powder (the major innovation of Pauly), a round bullet and either brass or paper casing. The cartridge was loaded through the breech and fired with a needle. The needle-activated centerfire breech-loading gun would become a major feature of firearms thereafter. Pauly made an improved version, protected by a patent, on 29 September 1812. Probably no invention connected with firearms has wrought such changes in the principle of gun construction as those effected by the "expansive cartridge case". This invention has completely  revolutionized the art of gun making, has been successfully applied to all descriptions of firearms, and has produced a new and important industry: that of cartridge manufacture. Its essential feature is preventing gas escaping the breech when the gun is fired, by means of an expansive cartridge case containing its own means of ignition. Previous to this invention shotguns and sporting rifles were loaded by means of powder flasks and shot bags or flasks, bullets, wads and copper caps, all carried separately. One of the earliest efficient modern cartridge cases was the pinfire cartridge, developed by French gunsmith Casimir Lefaucheux  in 1836. It consisted of a thin weak shell made of brass and paper that expanded from the force of the explosion. This fit perfectly in the barrel, and thus formed an efficient gas check. A small percussion cap was placed in the middle of the base of the cartridge and was ignited by means of a brass pin projecting from the side and struck by the hammer. This pin also afforded the means of extracting the cartridge case. This cartridge was introduced in England by Lang, of Cockspur Street, London, about 1845. In the American Civil War (1861–65) a  breech-loading rifle, the Sharps, was introduced and produced in large numbers. It could be loaded with either a ball or a paper cartridge. After that war many were converted to the use of metal cartridges. The development by Smith & Wesson (among many others) of revolver handguns that used metal cartridges helped establish cartridge firearms as the standard in the US by the late 1860s and early 1870s, although many continue to use percussion revolvers well after that. Modern metallic cartridges. Most of the early all-metallic cartridges were of the pinfire and rimfire types. The first centerfire metallic cartridge  was invented by Jean Samuel Pauly in the first decades of the 19th century. However, although it was the first cartridge to use a form of obturation, a feature integral to a successful breech-loading cartridge, Pauly died before it was converted to percussion cap ignition. 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). French gunsmith Benjamin Houllier improved the Lefaucheux pinfire cardboard cartridge and patented in Paris in 1846, the first fully metallic pinfire cartridge containing powder (and a pinfire), in a metallic cartridge. He also included in his patent claims rim and centerfire primed cartridges  using brass or copper casings. Houllier commercialised his weapons in association with the gunsmiths Blanchard or Charles Robert. In the United States, in 1857, the Flobert cartridge inspired the .22 Short (another rimfire), especially conceived for the first American revolver using rimfire cartridges, the Smith & Wesson Model 1. A year before, in 1856, the LeMat revolver was the first American (French-designed) breech-loading firearm, but it used pinfire cartridges, not rimfire. Formerly, an employee of the Colt's Patent Firearms Manufacturing Company, Rollin White, had been the first in America to conceive the idea of having the revolver cylinder  bored through to accept metallic cartridges ( 1852), with the first in the world to use bored-through cylinders probably having been Lefaucheux in 1845, who invented a pepperbox-revolver loaded from the rear using bored-through cylinders. Another possible claimant for the bored-through cylinder is a Frenchman by the name of Perrin, who allegedly produced in 1839 a pepperbox revolver with a bored-through cylinder to order. Other possible claimants include Devisme of France in 1834 or 1842 who claimed to have produced a breech-loading revolver in that period though his claim was later judged as lacking in  evidence by French courts and Hertog & Devos and Malherbe & Rissack of Belgium who both filed patents for breech-loading revolvers in 1853. However, Samuel Colt refused this innovation. White left Colt, went to Smith & Wesson to rent a licence for his patent, and this is how the S&W Model 1 saw light of day in 1857. The patent didn't definitely expire until 1870, allowing Smith & Wesson competitors to design and commercialise their own revolving breech-loaders using metallic cartridges. Famous models of that time are the Colts Open Top (1871–1872) and Single Action Army "Peacemaker" (1873). But in rifles , the lever-action mechanism patents were not obstructed by Rollin White's patent infringement because White only held a patent concerning drilled cylinders and revolving mechanisms. Thus, larger caliber rimfire cartridges were soon introduced after 1857, when the Smith & Wesson .22 Short ammunition was introduced for the first time. Some of these rifle cartridges were used in the American Civil War, including the .44 Henry and 56-56 Spencer (both in 1860). However, the large rimfire cartridges were soon replaced by centerfire cartridges, which could safely handle higher pressures. In 1867 the British war office adopted the Eley–Boxer metallic  centerfire cartridge case in the Pattern 1853 Enfield rifles, which were converted to Snider-Enfield breech-loaders on the Snider principle. This consisted of a block opening on a hinge, thus forming a false breech against which the cartridge rested. The priming cap was in the base of the cartridge and was discharged by a striker passing through the breech block. Other European powers adopted breech-loading military rifles from 1866 to 1868, with paper instead of metallic cartridge cases. The original Eley-Boxer cartridge case was made of thin-coiled brass—occasionally these cartridges could break apart and jam  the breech with the unwound remains of the case upon firing. Later the solid-drawn, centerfire cartridge case, made of one entire solid piece of tough hard metal, an alloy of copper, with a solid head of thicker metal, has been generally substituted. Centerfire cartridges with solid-drawn metallic cases containing their own means of ignition are almost universally used in all modern varieties of military and sporting rifles and pistols. Around 1870, machined tolerances had improved to the point that the cartridge case was no longer necessary to seal a firing chamber. Precision-faced bolts would seal as well , and could be economically manufactured. However, normal wear and tear proved this system to be generally infeasible. Nomenclature. The name of any given cartridge does not necessarily reflect any cartridge or gun dimension. The name is merely the standardized and accepted moniker. SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) and the European counterpart (CIP) and members of those organizations specify correct cartridge names. It is a common misconception to refer to a cartridge as a certain "caliber" (e.g., "30-06 caliber"), as the word "caliber" only describes the bullet diameter. The correct full name for this round is .30–'06 Springfield . The "-'06" means it was introduced in 1906. In sporting arms, the only consistent definition of "caliber" is bore diameter, and dozens of unique .30-caliber round types exist. There is considerable variation in cartridge nomenclature. Names sometimes reflect various characteristics of the cartridge. For example, the .308 Winchester uses a bullet of 308/1000-inch diameter and was standardized by Winchester. Conversely, cartridge names often reflect nothing related to the cartridge in any obvious way. For example, the .218 Bee uses a bullet of 224/1000-inch diameter, fired through a .22-in bore, etc. The 218 and Bee portions of  this cartridge name reflect nothing other than the desires of those who standardized that cartridge. Many similar examples exist, for example: .219 Zipper, .221 Fireball, .222 Remington, .256 Winchester, .280 Remington, .307 Winchester, .356 Winchester. Where two numbers are used in a cartridge name, the second number may reflect a variety of things. Frequently the first number reflects bore diameter (inches or millimeters). The second number reflects case length (in inches or mm). For example, the 7.62×51mm NATO refers to a bore diameter of 7.62 mm and has an overall case length of 51 mm, with a total length  of 71.1 mm. The commercial version is the .308 Winchester. In older black powder cartridges, the second number typically refers to powder charge, in grains. For example, the .50-90 Sharps has a .50-inch bore and used a nominal charge of of black powder. Many such cartridges were designated by a three-number system (e.g., 45–120–3 Sharps: 45-caliber bore, 120 grains of (black) powder, 3-inch long case). Other times, a similar three-number system indicated bore (caliber), charge (grains), and bullet weight (grains). The 45-70-500 Government is an example. Often, the name reflects the company  or individual who standardized it, such as the .30 Newton, or some characteristic important to that person. The .38 Special actually has a nominal bullet diameter of (jacketed) or (lead) while the case has a nominal diameter of , hence the name. This is historically logical: the hole drilled through the chambers of .36-caliber cap-and-ball revolvers when converting those to work with cartridges was , and the cartridge made to work in those revolvers was logically named the .38 Colt. The original cartridges used a heeled bullet like a .22 rimfire where the bullet was the same diameter as  the case. Early Colt Army .38s have a bore diameter that will allow a .357" diameter bullet to slide through the barrel. The cylinder is bored straight through with no step. Later versions used an inside the case lubricated bullet of .357" diameter instead of the original .38" with a reduction in bore diameter. The difference in .38 Special bullet diameter and case diameter reflects the thickness of the case mouth (approximately 11/1000-inch per side). The .357 Magnum evolved from the .38 Special. The .357 was named to reflect bullet diameter (in thousandths inch), not case diameter. "Magnum" was  used to indicate its longer case and higher operating pressure. Classification. Cartridges are classified by some major characteristics. One classification is the location of the primer. Early cartridges began with the pinfire, then the rimfire, and finally the centerfire. Another classification describes how cartridges are located in the chamber (headspace). Rimmed cartridges are located with the rim near the cartridge head; the rim is also used to extract the cartridge from the chamber. Examples are the .22 long rifle and .303 British. In a rimless cartridge, the cartridge head diameter is about the same as or smaller than the body  diameter. The head will have a groove so the cartridge can be extracted from the chamber. Locating the cartridge in the chamber is accomplished by other means. Some rimless cartridges are necked down, and they are positioned by the cartridge's shoulder. An example is the .30-06 Springfield. Pistol cartridges may be located by the end of the brass case. An example is the .45 ACP. A belted cartridge has a larger diameter band of thick metal near the head of the cartridge. An example is the .300 Weatherby Magnum. An extreme version of the rimless cartridge is the  rebated case; guns employing advanced primer ignition need such a case because the case moves during firing (i.e., it is not located at a fixed position). An example is the 20mm×110RB. Centerfire. A centerfire cartridge has a centrally located primer held within a recess in the case head. Most centerfire brass cases used worldwide for sporting ammunition use Boxer primers. It is easy to remove and replace Boxer primers using standard reloading tools, facilitating reuse. Some European- and Asian-manufactured military and sporting ammunition uses Berdan primers. Removing the spent primer from (decapping) these cases requires use of a special  tool because the primer anvil (on which the primer compound is crushed) is an integral part of the case and the case therefore does not have a central hole through which a decapping tool can push the primer out from the inside, as is done with Boxer primers. In Berdan cases, the flash holes are located to the sides of the anvil. With the right tool and components, reloading Berdan-primed cases is perfectly feasible. However, Berdan primers are not readily available in the U.S. Rimfire. Rimfire priming was a popular solution before centerfire priming was perfected. In a rimfire  case, centrifugal force pushes a liquid priming compound into the internal recess of the folded rim as the manufacturer spins the case at a high rate and heats the spinning case to dry the priming compound mixture in place within the hollow cavity formed within the rim fold at the perimeter of the case interior. In the mid- to late-1800s, many rimfire cartridge designs existed. Today only a few, mostly for use in small-caliber guns, remain in general and widespread use. These include the .17 Mach II, .17 Hornady Magnum Rimfire (HMR), 5mm Remington Magnum (Rem Mag), .22  (BB, CB, Short, Long, Long Rifle), and .22 Winchester Magnum Rimfire (WMR). Compared to modern centerfire cases used in the strongest types of modern guns, existing rimfire cartridge designs use loads that generate relatively low pressure because of limitations of feasible gun design – the rim has little or no lateral support from the gun. Such support would require very close tolerances in design of the chamber, bolt, and firing pin. Because that is not cost-effective, it is necessary to keep rimfire load pressure low enough so that the stress generated by chamber pressure that would push the case rim  outward cannot expand the rim significantly. Also, the wall of the folded rim must be thin and ductile enough to easily deform, as necessary to allow the blow from the firing pin to crush and thereby ignite the primer compound, and it must do so without rupturing, If it is too thick, it will be too resistant to deformation. If it is too hard, it will crack rather than deform. These two limitations – that the rim is self-supporting laterally and that the rim is thin and ductile enough to easily crush in response to the firing pin impact  – limit rimfire pressures. Modern centerfire cartridges are often loaded to about maximum chamber pressure. Conversely, no commercialized rimfire has ever been loaded above about maximum chamber pressure. However, with careful gun design and production, no fundamental reason exists that higher pressures could not be used. Despite the relative pressure disadvantage, modern rimfire magnums in .17-caliber/4.5mm, .20-caliber/5mm, and .22-caliber/5.6mm can generate muzzle energies comparable to smaller centerfire cartridges. Today, .22 LR (Long Rifle) accounts for the vast majority of all rimfire ammunition used. Standard .22 LR rounds use an essentially pure lead bullet plated with  a typical 95% copper, 5% zinc combination. These are offered in supersonic and subsonic types, as well as target, plinking, and hunting versions. These cartridges are usually coated with a hard wax for fouling control. The .22 LR and related rimfire .22 cartridges use a heeled bullet, where external diameter of the case is the same as diameter of the forward portion of the bullet and where the rearward portion of the bullet, which extends into the case, is necessarily smaller in diameter than the main body of the bullet. Semi-automatic vs. revolver cartridges. Most revolver cartridges are rimmed  at the base of the case, which seats against the edge of cylinder chamber to provide headspace control (to keep the cartridge from moving too far forward into the chamber) and to facilitate easy extraction. Nearly every centerfire semi-automatic pistol cartridge is "rimless", where the rim is of the same diameter as the case body but separated by a circumferential groove in between, into which the extractor engages the rim by hooking. A "semi-rimmed" cartridge is essentially a rimless one but the rim diameter is slightly larger than the case body, and a "rebated rimless" cartridge is one  with the rim smaller in diameter. All such cartridges headspace on the case mouth (although some, such as .38 Super, at one time seated on the rim, this was changed for accuracy reasons), which prevents the round from entering too far into the chamber. Some cartridges have a rim that is significantly smaller than case body diameter. These are known as rebated-rim designs and almost always allow a handgun to fire multiple caliber cartridges with only a barrel and magazine change. Projectile design types. The Hague Convention of 1899 bans the use of expanding projectiles against the military forces  of other nations. Some countries accept this as a blanket ban against the use of expanding projectiles against anyone, while others use JSP and HP against non-military forces such as terrorists and criminals. Common cartridges. Ammunition types are listed numerically. Snake shot. Snake shot (AKA: bird shot, rat shot and dust shot) refers to handgun and rifle rounds loaded with small lead shot. Snake shot is generally used for shooting at snakes, rodents, birds, and other pests at very close range. The most common snake shot cartridge is .22 Long Rifle loaded with No. 12 shot. From a standard  rifle these can produce effective patterns only to a distance of about – but in a smoothbore shotgun this can extend as far as . Caseless ammunition. Many governments and companies continue to develop caseless ammunition (where the entire case assembly is either consumed when the round fires or whatever remains is ejected with the bullet). So far, none of these have been successful enough to reach the civilian market and gain commercial success. Even within the military market, use is limited. Around 1848, Sharps introduced a rifle and paper cartridge (containing everything but the primer) system. When new these guns had  significant gas leaks at the chamber end, and with use these leaks progressively worsened. This problem plagues caseless cartridge and gun systems to this day. The Daisy Heddon VL Single Shot Rifle, which used a caseless round in .22 caliber, was produced by the air gun company, beginning in 1968. Apparently Daisy never considered the gun an actual firearm. In 1969, the ATF ruled it was in fact a firearm, which Daisy was not licensed to produce. Production of the guns and the ammo was discontinued in 1969. They are still available on the secondary market, mainly as collector items , as most owners report that accuracy is not very good. In 1989, Heckler & Koch, a prominent German firearms manufacturer, began advertising the G11 assault rifle, which shot a 4.73×33 square caseless round. The round was mechanically fired, with an integral primer. In 1993 Voere of Austria began selling a gun and caseless ammunition. Their system used a primer, electronically fired at 17.5 ± 2 volts. The upper and lower limits prevent fire from either stray currents or static electricity. The direct electrical firing eliminates the mechanical delays associated with a striker, reducing lock time and allowing for easier adjustment of  the rifle trigger. In both instances, the "case" was molded directly from solid nitrocellulose, which is itself relatively strong and inert. The bullet and primer were glued into the propellant block. Trounds. The "Tround" ("Triangular Round") was a unique type of cartridge designed in 1958 by David Dardick, for use in specially designed Dardick 1100 and Dardick 1500 open-chamber firearms. As their name suggests, Trounds were triangular in cross-section, and were made of plastic or aluminum, with the cartridge completely encasing the powder and projectile. The Tround design was also produced as a cartridge adaptor, to allow conventional  .38 Special and 22 Long Rifle cartridges to be used with the Dardick firearms. Blank ammunition. A blank is a charged cartridge that does not contain a projectile or alternatively uses a non-metallic (for instance, wooden) projectile that pulverizes when hitting a blank firing adapter. To contain the propellant, the opening where the projectile would normally be located is crimped shut and or it is sealed with some material that disperses rapidly upon leaving the barrel. This sealing material can still potentially cause harm at extremely close range. Actor Jon-Erik Hexum died when he shot himself in the  head with a blank, and actor Brandon Lee was famously killed during filming of "The Crow" when a blank fired behind a bullet that was stuck in the bore drove that bullet through his abdomen and into his spine. The gun had not been properly deactivated and a primed case with a bullet instead of a dummy had been used previously. Someone pulled the trigger and the primer drove the bullet silently into the bore. Blanks are used in training, but do not always cause a gun to behave the same as live ammunition does; recoil is always far weaker , and some automatic guns only cycle correctly when the gun is fitted with a blank-firing adaptor to confine gas pressure within the barrel to operate the gas system. Blanks can also be used to launch a rifle grenade, although later systems used a "bullet trap" design that captures a bullet from a conventional round, speeding deployment. This also negates the risk of mistakenly firing a live bullet into the rifle grenade, causing it to instantly explode instead of propelling it forward. Blanks are also used as dedicated launchers for propelling a grappling hook, rope line or flare, or for  a training lure for training gun dogs. The power loads used in a variety of nail guns are essentially rimfire blanks. Dummy rounds. Drill rounds are inert versions of cartridges used for education and practice during military training. Other than the lack of propellant and primer, these are the same size as normal cartridges and will fit into the mechanism of a gun in the same way as a live cartridge does. Because dry-firing (releasing the firing pin with an empty chamber) a gun can sometimes lead to firing pin (striker) damage, dummy rounds termed snap caps are designed  to protect centerfire guns from possible damage during "dry-fire" trigger control practices. To distinguish drill rounds and snap-caps from live rounds these are marked distinctively. Several forms of markings are used; e.g. setting colored flutes in the case, drilling holes through the case, coloring the bullet or cartridge, or a combination of these. In the case of centerfire drill rounds the primer will often be absent, its mounting hole in the base is left open. Because these are mechanically identical to live rounds, which are intended to be loaded once, fired and then discarded, drill rounds have a  tendency to become significantly worn and damaged with repeated passage through magazines and firing mechanisms, and must be frequently inspected to ensure that these are not so degraded as to be unusable—for example the cases can become torn or misshapen and snag on moving parts, or the bullet can become separated and stay in the breech when the case is ejected. Mek-Porek. The bright-colored Mek-Porek is an inert cartridge base designed to prevent a live round from being unintentionally chambered, to reduce the chances of an accidental discharge from mechanical or operator failure. An L-shaped  flag is visible from the outside, so that the shooter and other people concerned are instantly aware about the situation of the weapon. The Mek-Porek is usually tethered to its weapon by a short string, and can be quickly ejected to make way for a live round if the situation suddenly warrants. This safety device is standard-issue in the Israel Defense Forces. Snap cap. A snap cap is a device which is shaped like a standard cartridge but contains no primer, propellant or projectile. It is used to ensure that dry firing firearms of certain designs does not  cause damage. A small number of rimfire and centerfire firearms of older design should not be test-fired with the chamber empty, as this can lead to weakening or breakage of the firing pin and increased wear to other components in those firearms. In the instance of a rimfire weapon of primitive design, dry firing can also cause deformation of the chamber edge. For this reason some shooters use a snap cap in an attempt to cushion the weapon's firing pin as it moves forward. Some snap caps contain a spring-dampened fake primer, or one made of plastic , or none at all; the springs or plastic absorb force from the firing pin, allowing the user to safely test the function of the firearm action without damaging its components. Snap caps and action-proving dummy rounds also work as a training tool to replace live rounds for loading and unloading drills, as well as training for misfires or other malfunctions, as they function identically to a live "dud" round that has not ignited. Usually one snap-cap is usable for 300 to 400 clicks. After that, due to the hole at the false primer, the firing pin does not  reach it. Eco Friendly cartridges. They are meant to prevent pollution and are mostly biodegradable (metals being the exception) or fully. They are also meant to be used on older guns.