A firing pin or striker is a part of the firing mechanism of a

firearm A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and operated by an individual. The term is legally defined further in different countries (see legal definitions). The first firearms originate ...

that impacts the

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 te ...

in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spring acts directly on the firing pin to provide the impact force rather than it being struck by a

hammer A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nail (fastener), nails into wood, to sh ...

. The terms may also be used for a component of equipment or a device which has a similar function. Such equipment or devices include:

artillery Artillery consists of ranged weapons that launch Ammunition, munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during sieges, and l ...

munitions Ammunition, also known as ammo, is the material fired, scattered, dropped, or detonated from any weapon or weapon system. The term includes both expendable weapons (e.g., bombs, missiles, grenades, land mines), and the component parts of ...

and

pyrotechnics Pyrotechnics is the science and craft of creating fireworks, but also includes safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts (and other fasteners), parts of automotive airbags, as well as gas-pressure blasting in mining, q ...

Firearms

The typical firing pin is a thin, simple rod with a hardened, rounded tip that strikes and crushes the

. The rounded end ensures the primer is indented rather than pierced (to contain propellant gasses). It sits within a hole through the

breechblock A breechblock (or breech block) is the part of the firearm action that closes the breech of a breech loading weapon (whether small arms or artillery) before or at the moment of firing. It seals the breech and contains the pressure generated by ...

and is struck by the

when the

trigger Trigger may refer to: Arts, entertainment and media Fictional entities * Trigger (''Only Fools and Horses''), in the TV sitcom * Trigger Argee, in science fiction short stories by James H. Schmitz * Devil Trigger, a transformation ability of ...

is "pulled". A light firing-pin spring is often used to keep the firing pin rearward. It may be termed a ''firing-pin return spring'', since it returns it to the unfired position. In

semi-automatic firearm A semi-automatic firearm, also called a self-loading or autoloading firearm ( fully automatic and selective fire firearms are also variations on self-loading firearms), is a repeating firearm whose action mechanism automatically loads a follo ...

s, this prevents premature firing from the

inertia Inertia is the natural tendency of objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes the velocity to change. It is one of the fundamental principles in classical physics, and described by Isaac Newto ...

of the firing pin as the breech mechanism closes in the reloading part of the firing cycle. Firing pins of this type are often too short to contact the primer when the hammer is resting against it. This is a safety measure to prevent discharge from external forces such as a drop. Firing relies upon the transfer of

momentum In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...

from the hammer to give the firing pin sufficient impact energy to cause firing.

Type of cartridge

Animation of a

thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...

The two main types of metallic cartridges used in modern firearms are

centerfire Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center A center-fire (or centerfire) is a type of metallic cartridge used in firearms, where the primer is located at the center of the base of its casing (i. ...

and rimfire. In centerfire cartridges, the primer is located in the center of the base of the cartridge. Firing pins for centerfire cartridges usually have a round cross-section and their movement is usually through a hole in the breechblock along the axis of the center of the

barrel A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden stave (wood), staves and bound by wooden or metal hoops. The word vat is often used for large containers ...

's bore. Rimfire cartridges however, must be struck on the base about the rim of the cartridge. While rimfire firearms may use a firing pin with a round cross-section, it is common for them to be flat, with a square or rectangular cross-section and a blunt chisel point. Flat firing pins can be stamped from flat metal stock and usually operate in a slot cut in the breechblock (rather than a hole) that is parallel but offset from the centerline of the barrel. These production methods are generally simpler and reduce production costs. It is generally recommended not to excessively "dry fire" rimfire firearms (ie firing without a chambered round) as it is possible for the firing pin to strike the face of the camber and deform it or damage the firing pin.

Historical cartridges

In 1808 by the Swiss gunsmith

Jean Samuel Pauly Jean Samuel Pauly (1766 – c. 1821), born Samuel Johannes Pauli, was a Swiss inventor and gunsmith of the early 19th century. Parish records show that he was baptised in Vechigen near Bern, Switzerland on 13 April 1766, the son of Johann Pauli ...

in association with French gunsmith

François Prélat François Prélat was a Frenchman involved in gunmaking in the early part of the nineteenth century. It is sometimes claimed that he invented the first fully contained cartridge in 1808, as well as the percussion cap in 1818. However most gun hist ...

created the first cartridges to integrate a primer and be self-contained. The paper cartridge used a metal base with a through-hole coated in a percussive priming compound. Pauly also developed a breech-loading shotgun for his cartridge, using a firing pin and external hammer. The

Dreyse needle gun Dreyse may refer to: * Johann Nicolaus von Dreyse (1787–1867), German firearms inventor * Hitch Dreyse, a fictional List of Attack on Titan characters, character in ''Attack on Titan'' (''Shingeki no Kyojin'') series who serves in the military po ...

of 1836 uses a paper cartridge with a priming as part of a

sabot Sabot may refer to: * Sabot (firearms), disposable supportive device used in gunpowder ammunitions to fit/patch around a sub-caliber projectile * Sabot (shoe), a type of wooden shoe People * Dick Sabot (1944–2005), American economist and bus ...

which cradles the projectile and is forward of the propelling charge. The needle-like firing pin projects from the bolt-face and pierces the cartridge when the breech is closed. On firing, the spring-loaded needle strikes the priming in the sabot. Unlike Pauly's cartridge, which was not widely accepted, Dreyse's rifle was adopted by Prussia as its infantry

service rifle A service rifle (or standard-issue rifle) is a rifle a military issues to its regular infantry. In modern militaries, this is generally a versatile, rugged, and reliable assault rifle or battle rifle, suitable for use in nearly all environments ...

. It was the first military breechloader to use a self-contained cartridge and consequently, the first to employ a firing pin. The

pinfire cartridge The pin-fire (or pinfire) is an obsolete type of metallic cartridge used in firearms, where the Primer_(firearms), priming compound is ignited by striking a small pin that protrudes radially from above the base of the cartridge. Invented by Fr ...

patented in 1835, uses a metallic cartridge with an integrated firing pin located radially near the base of the cartridge. The pin needs to be aligned with a corresponding slot in the chamber; a disadvantage compared with rimfire and centerfire cartridges that followed and that are also safer.

Side-lock hammers

Early

rifle A rifle is a long gun, long-barreled firearm designed for accurate shooting and higher stopping power, with a gun barrel, barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus o ...

designs that fired metallic cartridges typically used a side-lock mechanism, with the hammer mounted to one side rather than inline with the axis of the barrel. In the trapdoor

Springfield Model 1865 The Springfield Model 1865 was an early breech-loading rifle manufactured by U.S. Springfield Armory. It was a modification of the Springfield Model 1861 with trapdoor mechanism, trapdoor action. It was replaced by the Springfield Model 1866, whi ...

(and similar) the rear of the firing pin tube within the breechblock is angled away from the centerline of the barrel toward the hammer. The

Sharps rifle Sharps rifles are a series of large-bore, single-shot, falling-block, breech-loading rifles, beginning with a design by Christian Sharps in 1848 and ceasing production in 1881. They were renowned for long-range accuracy. By 1874, the rifle ...

uses a firing pin block to solve this alignment problem. The block sits within a recess in the breechblock. When struck by the hammer, the whole block is propelled forward. That part of the block with the firing pin sits on the centerline of the barrel and strikes the primer.

Fixed firing pins

Many

revolver A revolver is a repeating handgun with at least one barrel and a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold six cartridges before needing to be reloaded, ...

s use a firing pin that is fixed to the hammer. Simple blowback sub-machine guns that fire from the

open-bolt A firearm is said to fire from an open bolt or open breech if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a car ...

position often have a fixed firing pin that protrudes from the face of the bolt. As the bolt fully closes on the breech the primer of the newly chambered round is struck, causing the cartridge to fire. The

Owen Owen may refer to: People and fictional characters * Owen (name), including a list of people and fictional characters with the given name or surname Places United States * Owen, Missouri, a ghost town * Owen, Wisconsin * Owen County, Indiana ...

and

F1 submachine gun The F1 is a 9x19mm Australian submachine gun manufactured by the Lithgow Small Arms Factory. First issued to Australian troops in July 1963, it replaced the Owen machine carbine. Like the Owen, the F1 had a distinctive top mounted magazine. It ...

are examples that use bolt-face fixed firing-pins. Some

mortars Mortar may refer to: * Mortar (weapon), an indirect-fire infantry weapon * Mortar (masonry), a material used to fill the gaps between blocks and bind them together * Mortar and pestle, a tool pair used to crush or grind * Mortar, Bihar, a village i ...

use a fixed firing pin mounted in the breech plug. When a mortar round is dropped down the barrel, a primer in the base of the mortar round strikes the firing pin and ignites the propelling charge.

Floating firing pins

In firearms terminology, a floating firing pin is one which is unrestricted by a firing-pin return spring or similar. While it will be captive and unable to simply fall out, either forward or backward, it is otherwise free to slide within these stops. The trapdoor

is an example of a floating firing pin.

Striker

Hammer-operated firing mechanisms use a relatively light firing pin and rely on a transfer of

received from a spring-loaded

, in the same fashion as a punch or

chisel A chisel is a hand tool with a characteristic Wedge, wedge-shaped cutting edge on the end of its blade. A chisel is useful for carving or cutting a hard material such as woodworking, wood, lapidary, stone, or metalworking, metal. Using a chi ...

relays the blow from a

mallet A mallet is a tool used for imparting force on another object, often made of rubber or sometimes wood, that is smaller than a maul or beetle, and usually has a relatively large head. General overview The term is descriptive of the ...

. In firearms terminology, a ''striker'' (or striker mechanism) derives the impact force to strike the primer from a spring acting directly upon the ''firing pin'' – similar to a

crossbow A crossbow is a ranged weapon using an Elasticity (physics), elastic launching device consisting of a Bow and arrow, bow-like assembly called a ''prod'', mounted horizontally on a main frame called a ''tiller'', which is hand-held in a similar f ...

, where the striker (firing pin) is like the

crossbow bolt A bolt or quarrel is a dart-like projectile used by crossbows. The word ''quarrel'' is from the Old French ''quarrel'' (> French ''carreau'') "square thing", specialized use as ''quarrel d'arcbaleste'' (> ''carreau d'arbalète'') "crossbow quar ...

(arrow). A striker mechanism is very common in

bolt-action Bolt action is a type of manual Action (firearms), firearm action that is operated by ''directly'' manipulating the bolt (firearms), turn-bolt via a cocking handle, bolt handle, most commonly placed on the right-hand side of the firearm (a ...

firearms but not to the exclusion of hammer-operated mechanisms. It is also found in other actions where the breechblock reciprocates directly inline with the axis of the barrel. A striker mechanism will consist of the striker spring (firing spring) and the striker. The striker spring is a relatively strong spring sufficient to initiate firing. A typical striker consists of a narrow striking point, a heavier section that acts as a spring guide for the striker spring, a shoulder to restrain the spring, and a catch piece which is engaged by the trigger sear to hold the spring under tension when "cocked" and ready to fire. The striker spring is compressed between the striker's shoulder and the rear of the breechblock. A striker may be assembled from several component; however, the stored energy in the striker spring is transferred directly to the striker and then to the primer without any intermediate transfer of energy or momentum. As striker mechanisms combine both functions of hammer and firing pin in one piece, they are generally considered to be mechanically simpler but are more robust in construction than a typical firing pin. Many small-

caliber In guns, particularly firearms, but not #As a measurement of length, artillery, where a different definition may apply, caliber (or calibre; sometimes abbreviated as "cal") is the specified nominal internal diameter of the gun barrel Gauge ( ...

rimfire bolt-action rifles and some centerfire automatic weapons (e. g., vz. 58) may appear to have a striker-operated firing mechanism but are actually a type of linear hammer. The hammer can be likened to that of a

pile driver A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams, and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pili ...

and is mainly contained within the bolt. It is much like the striker already described except that the "hammer" upon which the firing spring acts and the firing pin are separate units. Confusingly, parts lists will often refer to this type of hammer as a "striker". Striker-fired (or similar) bolt action firearms may be classified as ''cock-on-close'' or ''cock-on-open''.

Cock-on-close

When the breech is opened and retracted rearward, the striker is also carried rearward so that the striker catch passes over the trigger sear. When the bolt is pushed forward to close the breech, the striker catch is held by the trigger sear. The firer must close the bolt with sufficient force to overcome the force exerted by the cocking spring. Notably, the

Lee–Enfield The Lee–Enfield is a bolt-action, magazine-fed repeating rifle that served as the main firearm of the military forces of the British Empire and Commonwealth during the first half of the 20th century, and was the standard service rifle of th ...

and Belgian Mauser cock on closing as do many small-caliber rimfire bolt-action rifles.

Cock-on-open

The breech of a bolt action rifle is opened by first rotating the bolt handle. In cock-on-open operation, this rotation acts on a

cam Cam or CAM may refer to: Science and technology * Cam (mechanism), a mechanical linkage which translates motion * Camshaft, a shaft with a cam * Camera or webcam, a device that records images or video In computing * Computer-aided manufacturin ...

(similar to the action of a

screw thread A screw thread is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a ''straight'' thread and t ...

) which retracts the striker, compressing the cocking spring and holding it there. When the cocking handle is rotated closed, the cocking cam disengages but the striker is retained in the cocked position by the trigger sear. Introduced in the

Mauser Model 1871 The Mauser Model 1871, adopted as the 71 or 71, or "Infantry Rifle 71" ("I.G.Mod.71" was stamped on the rifles themselves), was the first rifle model in a distinguished line designed and manufactured by Paul Mauser and Wilhelm Mauser of the M ...

, it significantly reduced the risk of accidental discharge upon closing. The system of operation was widely adopted and is used almost exclusively in modern centerfire rifle designs. The Mauser

Gewehr 98 The Gewehr 98 (abbreviated ''G98'', Gew 98, or ''M98'') is a bolt-action rifle made by Mauser for the German Empire as its service rifle from 1898 to 1935. The Gewehr 98 action, using a 5-round stripper clip loaded with the 7.92×57mm Mauser ...

, the

Mosin–Nagant The Mosin–Nagant is a five-shot, Bolt action, bolt-action, Magazine (firearms), internal magazine–fed military rifle. Known officially as the 3-line rifle M1891, in Russia and the former Soviet Union as Mosin's rifle (, ISO 9: ) and inform ...

and

M1903 Springfield The M1903 Springfield, officially the U.S. Rifle, Caliber .30, M1903, is an American five-round magazine-fed, bolt-action service repeating rifle, used primarily during the first half of the 20th century. The M1903 was first used in combat ...

are examples of service rifles using this type of operation.

Other applications

Modern era

gun A gun is a device that Propulsion, propels a projectile using pressure or explosive force. The projectiles are typically solid, but can also be pressurized liquid (e.g. in water guns or water cannon, cannons), or gas (e.g. light-gas gun). So ...

s in general (and not just firearms) use a firing pin of some description to initiate firing. Mechanical contact

fuze In military munitions, a fuze (sometimes fuse) is the part of the device that initiates its function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fu ...

s in explosive ordnance will employ a firing pin or striker to initiate

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...

. Such devices include: artillery projectiles,

aerial bomb An aerial bomb is a type of Explosive weapon, explosive or Incendiary device, incendiary weapon intended to travel through the Atmosphere of Earth, air on a predictable trajectory. Engineers usually develop such bombs to be dropped from an aircra ...

s and

land mine A land mine, or landmine, is an explosive weapon often concealed under or camouflaged on the ground, and designed to destroy or disable enemy targets as they pass over or near it. Land mines are divided into two types: anti-tank mines, wh ...

s. In landmines, non-metallic firing pins, made from

ceramic A ceramic is any of the various hard, brittle, heat-resistant, and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcela ...

s for example, may be used to minimise their magnetic signature. The M127A1 signal rocket (and other similar

flare A flare, also sometimes called a fusée, fusee, or bengala, bengalo in several European countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illuminatio ...

s) have a primer in the base of the disposable launch tube. The cap contains a fixed firing-pin inside. The flare is fired by placing the cap over the base and striking it by hand. Hand

grenade A grenade is a small explosive weapon typically thrown by hand (also called hand grenade), but can also refer to a Shell (projectile), shell (explosive projectile) shot from the muzzle of a rifle (as a rifle grenade) or a grenade launcher. A mod ...

s of the type that use a safety lever (such as the

M26 grenade The M26 is a fragmentation hand grenade developed by the United States military. It entered service in 1952 and was first used in combat during the Korean War, replacing the Mk 2 of World War II. The M26 series was the primary fragmentation grena ...

) use a striker that is similar to the classic spring-loaded

mousetrap A mousetrap is a specialized type of animal trap designed primarily to catch and, usually, kill Mouse, mice. Mousetraps are usually set in an indoor location where there is a suspected infestation of rodents. Larger traps are designed to catch ...

. It is held under tension until the lever is released and then flips over to strike the primer cap. Some

chemical oxygen generator A chemical oxygen generator is a device that releases oxygen via a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate. Ozonides are a promising group of oxygen sources, as well. The generators are usu ...

s use a primer and mousetrap type striker to initiate the chemical reaction.

Images

Image:Grenade F1 ru.svg, Cutaway view of a Russian F1 fragmentation grenade showing firing pin Image:M1-M4 mine cutaway.JPG, Cutaway view of an M4 anti-tank mine showing integral firing pin Image:GYATA-64_cutaway.jpg, Gyata-64

anti-personnel mine An anti-personnel mine or anti-personnel landmine (APL) is a form of land mine, mine designed for use against human, humans, as opposed to an anti-tank mine, which target vehicles. APLs are classified into: blast mines and fragmentation mines; ...

Image:PM-79_mine_cutaway.png, PM-79 antipersonnel mine Image:Valmara_59_mine_cutaway.png,

Valmara 59 The Valmara 59 is a large cylindrical Italian bounding anti-personnel mine. It is the first in the "Valmara" family of mines produced by Valsella Meccanotecnica, and was followed by the Valmara 69 and VS-JAP. The mine's body is plastic with a ...

bounding mine A bounding mine is an anti-personnel mine designed to be used in open areas. When it is tripped, a small propelling charge launches the body of the mine into the air, where the main charge detonates and sprays fragmentation at roughly waist h ...

Image:MD82_mine_cutaway.JPG, MD-82 mine (

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

ese near-copy of the

M14 mine The M14 mine "Toepopper" is a small ( diameter) anti-personnel land mine first deployed by the United States circa 1955. The M14 mechanism uses a belleville spring to flip a firing pin downwards into a stab detonator when pressure is applied. On ...

) Image:Russian_-_MUV_pull_fuze.jpg, Military boobytrap firing device from

USSR The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

(normally connected to a

tripwire A tripwire is a passive triggering mechanism. Typically, a wire or cord is attached to a device for detecting or reacting to physical movement. Military applications Such tripwires may be attached to one or more mines⁠especially fragme ...

) showing integral striker. The detonator on the end is inserted into a block of explosive e.g.

Semtex Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, and in certain military applications. Semtex was developed and manufactured in Czechoslovakia, originally under the name B 1 a ...

Image:Russian_-_VPF_pull_fuze.jpg,

booby trap firing device—pull

: normally connected to a

Image:Russian_MV-5_pressure_fuze.jpg, USSR boobytrap firing device—pressure fuze: victim steps on loose floorboard with fuze concealed underneath. Image:BLU-43B_internal.jpg, Cross-sectional view of a

BLU-43 Dragontooth BLU-43/B and BLU-44/B (Bomb Live Unit) "Dragontooth" were air-dropped cluster-type land mines used by the United States during the Vietnam War. It is chemically activated and has a relatively low explosive content, typically maiming rather than ...

cluster munition A cluster munition is a form of air-dropped or ground-launched explosive weapon that releases or ejects smaller submunitions. Commonly, this is a cluster bomb that ejects explosive bomblets that are designed to kill personnel and destroy veh ...

showing firing pin,

detonator A detonator is a device used to make an explosive or explosive device explode. Detonators come in a variety of types, depending on how they are initiated (chemically, mechanically, or electrically) and details of their inner working, which of ...

and adjacent

explosive booster An explosive booster is a sensitive explosive charge that acts as a bridge between a (relatively weak) conventional detonator and a low-sensitivity (but typically high-energy) explosive such as TNT. By itself, the initiating detonator would not d ...

charge Image:Type_99_grenade.jpg, Cross-sectional view of a Japanese Type 99 grenade showing firing pin. Image:smine-sensor.jpg, Cross-sectional view of the fuze fitted to a German

S-mine The German S-mine (''Schrapnellmine'', ''Springmine'' or ''Splittermine'' in German), known by enemy Allied Forces as the "Bouncing Betty" on the Western Front and "frog-mine" on the Eastern Front, is the best-known version of a class of mines ...

Image:M2A4 mine M6A1 fuze.jpg, Cross-sectional view of an American

M2 mine The M2 is a United States bounding anti-personnel mine used during World War II. A number of variants of the mine were produced and although the mine is no longer in US service, it can be found in Cyprus, Iran, Iraq, Korea, Laos, Oman, Rwanda, T ...

Image:M14 mine cutaway - internal view.png, Cut-away view of an M14 antipersonnel landmine

References

External links

* {{Firearms Firearm components