primer (firearm)
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firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...
s and
artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during si ...
, the primer () is the chemical and/or device responsible for initiating the
propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the ...
combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...
that will push the
projectile A projectile is an object that is propelled by the application of an external force and then moves freely under the influence of gravity and air resistance. Although any objects in motion through space are projectiles, they are commonly found i ...
s out of the
gun barrel A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pres ...
. In early
black powder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
guns such as
muzzleloader A muzzleloader is any firearm into which the projectile and the propellant charge is loaded from the muzzle of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern (higher tech and harder to make) desig ...
s, the primer was essentially the same chemical as the main propellant (albeit usually in a finer-powdered form), but poured into an external flash pan, where it could be ignited by an ignition source such as a slow match or a
flintlock Flintlock is a general term for any firearm that uses a flint-striking ignition mechanism, the first of which appeared in Western Europe in the early 16th century. The term may also apply to a particular form of the mechanism itself, also know ...
though some muzzleloaders have primers like cap gun caps. This external powder was connected through a small opening at the rear of the gun barrel that led to the main charge within the barrel. As gunpowder will not burn when wet, this made it difficult (or even impossible) to fire these types of weapons in rainy or humid conditions. Modern primers, by contrast, are more specialized and distinct from the main propellant they are designed to ignite. They are of two types, those using shock-sensitive chemicals, and those reliant on chemicals ignited by an electric impulse. In smaller weapons the primer is usually of the first type and integrated into the base of a cartridge. Examples include
handgun A handgun is a short-barrelled gun, typically a firearm, that is designed to be usable with only one hand. It is distinguished from a long gun (i.e. rifle, shotgun or machine gun, etc.), which needs to be held by both hands and also braced ag ...
cartridges,
rifle A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
cartridges, and
shotgun A shotgun (also known as a scattergun, or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub- pr ...
shells. Larger artillery pieces in contrast typically use electric priming. In artillery the primers are frequently a separate component, placed inside the barrel to the rear of the main propellant charge—but there are other examples of guns, including for example some automatic weapons, designed to shoot cartridges with integral electric primers. Upon being struck with sufficient force generated by the firing pin, or electrically ignited, primers react chemically to produce heat, which gets transferred to the main propellant charge and ignites it, and this, in turn, propels the projectile. Due to their small size, these primers themselves lack the power to shoot the projectile, but still have enough energy to drive a bullet partway into the barrel — a dangerous condition called a
squib load A squib load, also known as a squib round, pop and no kick, or just a squib, is a firearm malfunction in which a fired projectile does not have enough force behind it to exit the barrel, and thus becomes stuck. This type of malfunction can be ex ...
.


Priming methods

The first step to firing a firearm of any sort is igniting the propellant. The earliest firearms were
hand cannon The hand cannon ( Chinese: 手 銃 ''shŏuchòng'', or 火 銃 ''huŏchòng''), also known as the gonne or handgonne, is the first true firearm and the successor of the fire lance. It is the oldest type of small arms as well as the most mech ...
s, which were simple closed tubes. There was a small aperture, the "touchhole", drilled in the closed end of the tube, leading to the main powder charge. This hole was filled with finely ground powder, which was then ignited with a hot
ember An ember, also called a hot coal, is a hot lump of smouldering solid fuel, typically glowing, composed of greatly heated wood, coal, or other carbon-based material. Embers (hot coals) can exist within, remain after, or sometimes preced ...
or
torch A torch is a stick with combustible material at one end, which is ignited and used as a light source. Torches have been used throughout history, and are still used in processions, symbolic and religious events, and in juggling entertainment. I ...
. With the advent of hand-held firearms, this became an undesirable way of firing a gun. Holding a burning stick while trying to pour a charge of black powder carefully down a barrel is dangerous, and trying to hold the gun with one hand while simultaneously aiming at the target and looking for the touchhole makes it very difficult to fire accurately.


External priming


Matchlock

The first attempt to make the process of firing a small arm easier was the "matchlock". The matchlock incorporated a "lock" (so-called because of its resemblance to door locks of the day) that was actuated by a trigger, originally called a "tricker." The lock was a simple lever which pivoted when pulled and lowered the
match A match is a tool for starting a fire. Typically, matches are made of small wooden sticks or stiff paper. One end is coated with a material that can be ignited by friction generated by striking the match against a suitable surface. Wooden mat ...
down to the touchhole. The match was a slow-burning
fuse Fuse or FUSE may refer to: Devices * Fuse (electrical), a device used in electrical systems to protect against excessive current ** Fuse (automotive), a class of fuses for vehicles * Fuse (hydraulic), a device used in hydraulic systems to protect ...
made of plant fibers that were soaked in a solution of
nitrates Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insolu ...
,
charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, ...
, and
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...
, and dried. This "slow-match" was ignited before the
gun A gun is a ranged weapon designed to use a shooting tube (gun barrel) to launch projectiles. The projectiles are typically solid, but can also be pressurized liquid (e.g. in water guns/cannons, spray guns for painting or pressure washing, p ...
was needed, and it would slowly burn, keeping a hot ember at the burning end. After the gun was loaded and the touchhole primed with powder, the burning tip of the match was positioned so that the lock would bring it into contact with the touchhole. To fire the gun, it was aimed and the trigger pulled. This brought the match down to the touchhole, igniting the powder. With careful attention, the slow-burning match could be kept burning for long periods of time, and the use of the lock mechanism made fairly accurate fire possible.


Wheellock

The next revolution in ignition technology was the "wheel-lock". It used a spring-loaded,
serrated Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied p ...
steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
wheel A wheel is a circular component that is intended to rotate on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machines. Wheels, in conjunction wi ...
which rubbed against a piece of
iron pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...
, similar to a modern
lighter A lighter is a portable device which creates a flame, and can be used to ignite a variety of items, such as cigarettes, gas lighter, fireworks, candles or campfires. It consists of a metal or plastic container filled with a flammable liquid or c ...
. A key was used to wind the wheel and put the spring under tension. Once tensioned, the wheel was held in place by a trigger. When the trigger was pulled, the serrated edge of the steel rubbed against the pyrite, generating sparks. These sparks were directed into a pan, called the " flash pan", filled with loose powder which led into the touchhole. The flashpan usually was protected by a spring-loaded cover that would slide out of the way when the trigger was pulled, exposing the powder to the sparks. The wheel-lock was a major
innovation Innovation is the practical implementation of ideas that result in the introduction of new goods or services or improvement in offering goods or services. ISO TC 279 in the standard ISO 56000:2020 defines innovation as "a new or changed entity ...
— since it did not rely on burning material as a source of
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
, it could be kept ready for extended periods of time. The covered flashpan also provided some ability to withstand bad weather. Wind, rain, and wet weather would render a matchlock useless, but a wheel-lock that was loaded and waterproofed with a bit of grease around the flashpan could be fired under most conditions.


Flintlock

The wheel-lock enjoyed only a brief period of popularity before being superseded by a simpler, more robust design. The "flintlock", like the wheel-lock, used a flashpan and a spark to ignite the powder. As the name implies, the flintlock used
flint Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and start fir ...
rather than iron pyrite. The flint was held in a spring-loaded arm, called the "cock" from the resemblance of its motion to a pecking chicken. The cock rotated through approximately a 90-degree arc and was held in the tensioned, or "cocked" position by a trigger. Usually, flintlocks could lock the cock in two positions. The "half-cock" position held the cock halfway back, and used a deep notch so that pulling the trigger would not release the cock. Half-cock was a safety position, used when loading, storing or carrying a loaded flintlock. The "full-cock" position held the cock all the way back and was the position from which the gun was fired. The L-shaped "frizzen" was the other half of the flintlock's ignition system. It served as both a flashpan cover and a steel striking surface for the flint. The frizzen was hinged and spring-loaded so that it would lock in the open or closed position. When closed, the striking surface was positioned so that the flint would strike at the proper angle to generate a spark. The striking flint would also open the
frizzen The frizzen, historically called the "hammer" or the steel,This may appear anomalous since, in later firearm designs (e.g. percussion locks), the component operating in the same manner as the ''cock'' is called the hammer. is an "L"-shaped piece o ...
, exposing the flashpan to the spark. The flintlock mechanism was simpler and stronger than the wheel-lock, and the flint and steel provided a good, reliable source of ignition. The flintlock remained in military service for over 200 years, and flintlocks are still made today for historical re-enactments and muzzle-loading target competition, and for hunters who enjoy the additional challenge that the flintlock provides.


Caplock

The next major leap in ignition technology was the invention of the chemical primer, or "cap", and the mechanism which used it, called the "caplock". Percussion ignition was invented by Scottish clergyman Rev. Alexander John Forsyth in 1807 but needed further refinements before it was gradually accepted in the 1820s to 1830s. By the middle of the 19th century, the percussion or caplock system was well established. It was adopted by both sides in the
American Civil War The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...
, as it was simpler and more reliable than the flintlock. The main reason the caplock was so quickly adopted was its similarity to the flintlock and the ease of converting older arms to use percussion-cap ignition; usually, the same lock and barrel could be used with minor changes. The flashpan and frizzen were removed and replaced by a small, hollow horizontal cylinder (drum) screwed into the bored-out and tapped flash hole and carrying a "nipple" over which the cap could be fitted. A "hammer" which also had half-cock (for loading and applying the cap) and full-cock positions replaced the cock. When released by pulling the trigger, the hammer would strike the cap, crushing it against the nipple. The
percussion cap The percussion cap or percussion primer, introduced in the early 1820s, is a type of single-use percussion ignition device for muzzle loader firearm locks enabling them to fire reliably in any weather condition. This crucial invention gave rise t ...
was a thin metal cup that contained a small quantity of pressure-sensitive explosive, often
mercury fulminate Mercury(II) fulminate, or Hg(CNO)2, is a primary explosive. It is highly sensitive to friction, heat and shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though its chemical formu ...
. When crushed, the explosive would detonate, sending a stream of hot
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
down through a hole in the nipple and into the touchhole of the gun to ignite the powder charge. In the process of firing, the cap generally split open and would fall off when the hammer was moved to the half-cock position for loading. The caplock system worked well, and is still the preferred method of ignition for
hunter Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
s and recreational shooters who use
muzzle-loading A muzzleloader is any firearm into which the projectile and the propellant charge is loaded from the muzzle of the gun (i.e., from the forward, open end of the gun's barrel). This is distinct from the modern (higher tech and harder to make) desig ...
arms.


Electric-fired

A small number of
caseless Caseless ammunition (CL), or rather caseless cartridge, is a configuration of weapon-cartridge that eliminates the cartridge case that typically holds the primer, propellant and projectile together as a unit. Instead, the propellant and primer ...
cartridges use no primer at all, but the primary propellant is ignited using an externally provided electric charge, such as with the
Voere VEC-91 The Voere VEC-91 is a rifle made by Voere and was the first commercial sporting rifle to combine caseless ammunition and electronic firing. Depending upon its chambering, it fired a 5.56 (0.223"), 5.7 mm or 6 mm projectile at muzzle ve ...
and the O'Dwyer VLe. This is not to be confused with an electrically ignited internal primer (see below).


Internal priming

Chemical primers, advanced
metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...
and
manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...
techniques all came together in the 19th century to create an entirely new class of firearm — the cartridge arm. Flintlock and caplock shooters had long carried their
ammunition Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...
in
paper cartridge A paper cartridge is one of various types of small arms ammunition used before the advent of the metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and in some cases, a primer or a lub ...
s, which served to hold a measured charge of powder and a
bullet A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. Bullets are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax. Bullets are made in various shapes and co ...
in one convenient package; the paper also served to seal the bullet in the bore. Still, the source of ignition was handled separately from the cartridge. With the advent of chemical primers, it was not long before several systems were invented with many different ways of combining bullet, powder, and primer into a single package which could be loaded quickly from the
breech Breech may refer to: * Breech (firearms), the opening at the rear of a gun barrel where the cartridge is inserted in a breech-loading weapon * breech, the lower part of a pulley block * breech, the penetration of a boiler where exhaust gases leav ...
of the firearm. This greatly streamlined the reloading procedure and paved the way for semi- and fully automatic firearms. 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 be reloaded once it has been fired, adopting brass cartridge cases brought in the problems of extraction and ejection. The mechanism of a modern gun not only must load and fire the piece, but also must remove the spent case, which may require just as many moving parts. Many malfunctions involve this process, either through failure to extract a case properly from the chamber or by allowing it to jam the action. Nineteenth-century inventors were reluctant to accept this added complication and experimented with a variety of self-consuming cartridges before acknowledging that the advantages of brass cases far outweighed their one drawback. The three systems of self-contained metallic cartridge ignition which have survived the test of time are the rimfire, the Berdan
centerfire Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing (i.e. "case head"). Unlike rim ...
primer, and the Boxer centerfire primer.


Pinfire

A pinfire firearm cartridge is an obsolete type of brass cartridge in which the priming compound is ignited by striking a small pin which protrudes radially from just above the base of the cartridge. Invented by Casimir Lefaucheux in 1828 but not patented until 1835, it was one of the earliest practical designs of metallic cartridge. However, the protruding pin was vulnerable to damage, displacement and accidental ignition. Moreover, the pin had to be positioned carefully in a small notch when loading, making the pinfire's use in repeating or self-loading weapons impossible. The pinfire survives today only in a few very small blank cartridges designed as noisemakers and in novelty miniature guns.


Rimfire

Rimfire cartridges use a thin
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...
case with a hollow bulge, or rim, around the back end. This rim is filled during manufacture with an impact-sensitive primer. In the wet state, the primer is stable; a pellet of wet primer is placed in the shell and simply spun out to the full extremes of the rim. (For more on the exact process and one set of chemical compounds that have been used successfully, see , a 1932 Remington Arms patent by James E. Burns.) In the dry state, the primer within the rim becomes impact-sensitive. When the rim is then crushed by the hammer or firing pin, the primer detonates and ignites the powder charge. Rimfire cartridges are single-use and normally cannot be reloaded. Also, since the rim must be thin enough to be easily crushed, the peak pressure possible in the case is limited by the strength of this thin rim. Rimfire cartridges originally were available in
caliber In guns, particularly firearms, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge (firearms) , bore – regardless of how or where the bore is measured and whether the f ...
s up to 1" (100 caliber), however, all but the small .22 caliber rounds eventually died out. The
.22 Long Rifle The .22 Long Rifle or simply .22 LR or 22 (metric designation: 5.6×15mmR) is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of rifles, pistols, revolvers, smo ...
, also fired in
pistol A pistol is a handgun, more specifically one with the chamber integral to its gun barrel, though in common usage the two terms are often used interchangeably. The English word was introduced in , when early handguns were produced in Europe, an ...
s, is the most popular recreational caliber today because it is inexpensive, quiet, and has very low
recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force requ ...
. While the rimfire priming method is limited due to the thin cases required, it has enjoyed a few resurgences recently. First was Winchester's .22 Magnum Rimfire, or .22 WMR, in the 1950s, followed in 1970 by Remington's short-lived 5mm Rimfire, based on Winchester's magnum case. In 2002
Hornady Hornady Manufacturing Company is an American manufacturer of ammunition cartridges, components and handloading equipments, based in Grand Island, Nebraska. History The company is currently run by Joyce Hornady's son, Steve Hornady, who took over ...
introduced a new .17 caliber cartridge based on the .22 WMR, the
.17 HMR .17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by Hornady in 2002. It was developed by necking down a .22 Magnum case to take a .17 caliber (4.5 mm) projectile. Commonly loaded with a 1 ...
. The .17 HMR is essentially a .22 WMR cartridge necked down to accept a .17-caliber bullet and is used as a flat-shooting, light-duty
varmint Vermin (colloquially varmint(s) or varmit(s)) are pests or nuisance animals that spread diseases or destroy crops or livestock. Since the term is defined in relation to human activities, which species are included vary by region and enterpri ...
round. The .17 HMR was followed a year later by Hornady's .17 Mach 2, or
.17 HM2 The .17 Hornady Mach 2, or .17 HM2, is a rimfire cartridge introduced in 2004 by the ammunition manufacturer Hornady, following the successful launch in 2002 of the .17 HMR. The .17 HM2 is based on the .22 Long Rifle "Stinger" case, necked d ...
, which is based on a slightly lengthened and necked-down .22 Long Rifle cartridge. Both of the .17 caliber rimfires have had widespread support from firearms makers, and while the high-tech, high-velocity .17 caliber jacketed bullets make the
.17 Rimfire Below is a list of rimfire cartridges, ordered by caliber, small to large. Rimfire ammunition is a type of metallic cartridge whose primer is located within a hollow circumferential rim protruding from the base of its casing. Among the most com ...
cartridges quite a bit more expensive than the .22 caliber versions, they are excellent for shorter-range shooting and still far less expensive than comparable centerfire cartridges. In 2013, Winchester released the
.17 Winchester Super Magnum .17 Winchester Super Magnum, is a rimfire rifle cartridge developed by the ammunition company Winchester in 2012. It descended from the .27 caliber nail-gun blank by necking down the blank case to take a .17 caliber In guns, particu ...
, which utilizes the larger case of the long-obsolete .25 Stevens allowing for velocities approaching 3000fps with a 20gr bullet and making it the world's fastest rimfire round.


Centerfire

The identifying feature of centerfire ammunition is the metal cup containing the primer inserted into a recess in the center of the base of the cartridge. The firearm firing pin crushes this explosive between the cup and an anvil to produce hot gas and a shower of
incandescent Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its high temperature. The term derives from the Latin verb ''incandescere,'' to glow white. A common use of incandescence is ...
particles to ignite the powder charge. Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association p.65 Berdan and Boxer primers are used in centerfire cartridges; the primers differ in construction. Various priming mixtures have been used in different sized primers to effect prompt ignition of the powder charge. Particles with relatively high
heat capacity Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat capacity i ...
are required to promptly ignite
smokeless powder Finnish smokeless powderSmokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to gunpowder ("black powder"). The combustion products are mainly gaseous, compared to a ...
deterrent coatings. Some priming explosives decompose into incandescent solids or liquids. Inert ingredients may be heated into incandescent sparks when the explosive decomposes into gas. Cartridges for military use require stable priming formulations so war reserves of small-arms ammunition will dependably function after years of storage. Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association p.21


Electric-primed

Some rapid-fire, and larger military gun and
autocannon An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bull ...
rounds (such as the M50 20mm) utilize an internal electric primer that contains chemicals activated by an externally provided electric charge, as opposed to a mechanical impact. The primer in turn ignites the main propellant, just as with a shock-sensitive or external electric type. Among the advantages this brings is the ability, in an automatic weapon, to control the moment of cartridge ignition partially independently of the mechanical action of the gun. Historically this flexibility was employed by the German Luftwaffe in WW II, in the unusually efficient
synchronization gear A synchronization gear (also known as a gun synchronizer or interrupter gear) was a device enabling a single-engine tractor configuration aircraft to fire its forward-firing armament through the arc of its spinning propeller without bullets strik ...
that enabled machine guns and autocannon to be fired through the moving propellers of their fighter aircraft with a relatively small compromise in the guns' output of automatic fire. Other countries such as the Soviet Union relied on cruder mechanical systems, which reduced the rate of fire of their guns more severely. Electric priming was also used in the EtronX system developed and sold by Remington for some of its sporting rifles. It was sold as a firearm with a much faster lock time. It never became a popular sporting arms system and was discontinued by Remington as a result.


Primer actuated blowback

Primer actuated firearms use the energy of
primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a t ...
setback to unlock and cycle the firearm.
John Garand Jean Cantius Garand (; January 1, 1888 – February 16, 1974), also known as John C. Garand, was a Québec-born American designer of firearms who created the M1 Garand, a semi-automatic rifle that was widely used by the U.S. Army and U.S ...
developed the system in an unsuccessful bid to replace the M1903 bolt-action rifle in the early 1920s. Garand's prototypes worked well with US military .30-06 ammunition and uncrimped primers, but then the military changed from a fast burning gunpowder to a progressive burning Improved Military Rifle (IMR) powder. The slower pressure rise made the primer actuated prototypes unreliable, so Garand abandoned the design for a gas operated rifle that became the
M1 Garand The M1 Garand or M1 rifleOfficially designated as U.S. rifle, caliber .30, M1, later simply called Rifle, Caliber .30, M1, also called US Rifle, Cal. .30, M1 is a semi-automatic rifle that was the service rifle of the U.S Army during World War ...
. AAI Corporation used a primer piston in a rifle submitted for the SPIW competition. Other rifles to use this system were the Postnikov APT and Clarke carbine as described in . A similar system is used in the spotting rifles on the
LAW 80 The LAW 80 (Light Anti-armour Weapon 80), regularly referred to as LAW 94 in British service, is a man-portable, disposable anti-tank weapon previously used by the British Army and a few other militaries. Description The weapon consists of an ext ...
and
Shoulder-launched Multipurpose Assault Weapon The Mk 153 Shoulder-Launched Multipurpose Assault Weapon (SMAW) is a smoothbore shoulder-fired rocket launcher. It is a portable assault weapon (i.e. bunker buster) and has a secondary anti-armor capability. Developed from the B-300, it was intr ...
use a 9mm,
.308 Winchester The .308 Winchester is a smokeless powder rimless bottlenecked rifle cartridge widely used for hunting, target shooting, police, military, and personal protection applications globally. It is similar but not identical to the 7.62×51mm NATO ...
based cartridge with a .22 Hornet blank cartridge in place of the primer. Upon firing, the Hornet case sets back a short distance, unlocking the action.


Primer actuated cartridges

Primer actuated cartridges/Piston primer cartridges use a primer in the form of a blank to contain the propellant within the cartridge, or as a piston to unlock the bolt and cycle the weapons operation. Examples are the 9x51mm SMAW, MBA Javette and the M48A2.


See also

*
Lead(II) azide Lead(II) azide is an inorganic compound. More so than other azides, is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder. Preparation and handling Lead(II) azide is ...
*
Lead styphnate Lead styphnate (lead 2,4,6- trinitroresorcinate, C6HN3O8Pb ), whose name is derived from styphnic acid, is an explosive used as a component in primer and detonator mixtures for less sensitive secondary explosives. Lead styphnate is only slightly ...


References


External links

*. Thirteen chemicals used in U.S. Army small arms cartridges; 7 chemicals are not available within the U.S. *, p. 2-3 stating "1602–1604.
Fulminating gold Fulminating gold is a light- and shock-sensitive yellow to yellow-orange amorphous heterogeneous mixture of different polymeric compounds of predominantly gold (III), ammonia, and chlorine that cannot be described by a chemical formula. Here, the ...
, later used as a priming explosive, was invented by Johann Tholden, a Dutch chemist in the employ of the British Navy." Later, on same page, "1628. Gold fulminate priming explosives for torpedoes were invented by J. Thollen for the British Navy." *{{Citation , last=Urbański , first=Tadeusz , last2=Jurecki , first2=Marian (translator) , editor-last=Laverton , editor-first=Sylvia , date=1967 , edition=First English , title=Chemistry and Technology of Explosives , publisher=Pergammon , volume=III , lccn=63-10077 , ref=none c.f. p. 129.
Basilius Valentinus Basil Valentine is the Anglicised version of the name Basilius Valentinus, ostensibly a 15th-century alchemist, possibly Canon of the Benedictine Priory of Saint Peter in Erfurt, Germany but more likely a pseudonym used by one or several 16th-ce ...
described " explosive gold" in first half of 17th century. In 1630, Van Drebbel ( Cornelis Drebbel?) investigated fulminate of mercury and "explosive gold". In 1690,
Johann von Löwenstern-Kunckel Johann Kunckel, awarded Swedish nobility in 1693 under the Swedish name von Löwenstern-Kunckel and the German version of the name Kunckel von Löwenstern (1630 - prob. 20 March 1703), German chemist, was born in 1630 (or 1638), near Rendsburg, hi ...
's book ''Laboratorium Chymicum'' described how to make fulminate of mercury. In 1805, Alexander John Forsyth used potassium chlorate to make pellets, but these were not safe. "The first ignition caps were invented in the early nineteenth century. In these caps the ignitable composition was enclosed in a casing of brass or copper. This invention cannot be traced with any certainty to any individual. The literature on the subject names several chemists including Bellot and Egg in 1815 The first application of mercury fulminate in ignition caps is attributed to Wright in 1823." Ammunition