A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer 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 nails into wood, to shape metal (as ...

. 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 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 sieg ...

munitions 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 weapo ...

and

pyrotechnics Pyrotechnics is the science and craft of creating such things as fireworks, safety matches, oxygen candles, Pyrotechnic fastener, explosive bolts and other fasteners, parts of automotive airbags, as well as gas-pressure blasting in mining, quarry ...

Firearms

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

s, this prevents premature firing from the

inertia Inertia is the idea that an object will continue its current motion until some force causes its speed or direction to change. The term is properly understood as shorthand for "the principle of inertia" as described by Newton in his first law o ...

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 (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. If is an object's mass ...

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 thu ...

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 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 ri ...

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 staves and bound by wooden or metal hoops. The word vat is often used for large containers for liquids, ...

'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 in association with French gunsmith François Prélat 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 character in '' Attack on Titan'' (''Shingeki no Kyojin'') series who serves in the military police Military police (MP) ar ...

of 1836 uses a paper cartridge with a priming as part of a sabot 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 regular infantry. In modern militaries, this is typically a versatile and rugged battle rifle, assault rifle, or carbine suitable for use in nearly all environments. Mos ...

. It was the first military breechloader to use a self-contained cartridge and consequently, the first to employ a firing pin. The pinfire cartridge 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 center fire cartridges that followed and that are also safer.

Side-lock hammers

Early rifle 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 (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 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 revolvers use a firing pin that is fixed to the hammer. Simple blowback sub-machine guns that fire from the open-bolt 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 and F1 submachine gun are examples that use bolt-face fixed firing-pins. Some mortars 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 Springfield Model 1865 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 Punch commonly refers to: * Punch (combat), a strike made using the hand closed into a fist * Punch (drink), a wide assortment of drinks, non-alcoholic or alcoholic, generally containing fruit or fruit juice Punch may also refer to: Places * Pun ...

chisel A chisel is a tool with a characteristically shaped cutting edge (such that wood chisels have lent part of their name to a particular grind) of blade on its end, for carving or cutting a hard material such as wood, stone, or metal by hand, s ...

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. The term is descriptive of the overall size and propor ...

. 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 elastic launching device consisting of a bow-like assembly called a ''prod'', mounted horizontally on a main frame called a ''tiller'', which is hand-held in a similar fashion to the stock of a long fir ...

, where the striker (firing pin) is like the

crossbow bolt A bolt or quarrel is a dart-like projectile used by crossbows. The name "quarrel" is derived from the French word ''carré'', meaning square, referring to their typically square heads. Although their lengths vary, bolts are typically shorter and ...

(arrow). A striker mechanism is very common in

bolt action Bolt-action is a type of manual firearm action that is operated by ''directly'' manipulating the bolt via a bolt handle, which is most commonly placed on the right-hand side of the weapon (as most users are right-handed). Most bolt-action ...

firearms but not to the exclusion of a hammer-operated mechanisms. It will also be 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 calibre 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 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 or 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 British Army's s ...

and Belgian Mauser cock on closing as do many small calibre 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 (similar to the action of a

screw thread A screw thread, often shortened to 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 ...

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

Gewehr 98 The Gewehr 98 (abbreviated G98, Gew 98, or M98) is a German bolt-action rifle made by Mauser, firing cartridges from a five-round internal clip-loaded magazine. It was the German service rifle from 1898 to 1935, when it was replaced by the K ...

, the

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

and M1903 Springfield are examples of service rifles using this type of operation.

Other applications

Modern era guns 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 function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fuze de ...

s in explosive ordinance 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 or incendiary weapon intended to travel through the air on a predictable trajectory. Engineers usually develop such bombs to be dropped from an aircraft. The use of aerial bombs is termed aerial bombing. ...

s and

land mine A land mine is an explosive device concealed under or on the ground and designed to destroy or disable enemy targets, ranging from combatants to vehicles and tanks, as they pass over or near it. Such a device is typically detonated automatic ...

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, porcelai ...

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 in some Latin-speaking countries, is a type of pyrotechnic that produces a bright light or intense heat without an explosion. Flares are used for distress signaling, illumination, o ...

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

s of the type that use a safety lever (such as the M26 grenade) use a striker that is similar to the classic spring-loaded mousetrap. It is held under tension until the lever is released and then flips over to strike the primer cap. Some chemical oxygen generators 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 Anti-personnel mines are a form of mine designed for use against humans, as opposed to anti-tank mines, which are designed for use against vehicles. Anti-personnel mines may be classified into blast mines or fragmentation mines; the latter ma ...

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 Image:MD82_mine_cutaway.JPG, MD-82 mine (

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making it ...

ese near-copy of the M14 mine) Image:Russian_-_MUV_pull_fuze.jpg, Military

boobytrap A booby trap is a device or setup that is intended to kill, harm or surprise a human or another animal. It is triggered by the presence or actions of the victim and sometimes has some form of bait designed to lure the victim towards it. The trap m ...

firing device from

USSR The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

(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 mines – especially fragm ...

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

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 vehic ...

showing firing pin, detonator and adjacent explosive booster 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 Image:M2A4 mine M6A1 fuze.jpg, Cross-sectional view of an American M2 mine Image:M14 mine cutaway - internal view.png, Cut-away view of an M14 antipersonnel landmine

References

{{Firearms Firearm components