Firing pin
Encyclopedia
A firing pin or striker is part of the firing mechanism used in a firearm
or explosive device e.g. an M14
landmine or bomb
fuze
. Firing pins may take many forms, though the types used in landmines, bombs, grenade
fuzes or other single-use devices generally have a sharpened point. In contrast, firing pins used in firearms usually have a small, rounded portion designed to strike the primer
of a cartridge
, detonating the priming compound, which then ignites the propellant
(in the case of firearms) or fires the detonator
and booster
.
to the primer, while a striker is usually heavier, and is directly connected to the spring providing the energy to impact the primer. Striker mechanisms are generally simpler, since they combine the functions of hammer and firing pin in one.
The firing pin or striker is generally located in the bolt of a repeating firearm. Firearms that do not have bolts, such as revolver
s and many types of single-shot
actions, generally have a very short firing pin in the frame, or else attached to the hammer itself. These types of firearms are almost never striker fired, as there is insufficient space to house a striker mechanism. Strikers are most commonly found in pistol
s and bolt action firearms.
The typical firing pin is a small rod of steel
, with the end that strikes the primer rounded into a hemispherical shape and hardened. The rounded end ensures the primer is indented rather than pierced, as would happen if the firing pin were sharply pointed. Most firing pins have a spring to push them out of contact with the primer, and often will have an integrated passive safety mechanism, such as a block that prevents them from moving forward unless the trigger is depressed, or a transfer bar, also trigger actuated, that must be in place to allow the hammer to depress the firing pin. This safety is in addition to any manually operated safety or safeties that act to block the trigger or hammer.
Firearms that use long firing pins, such as pistols, will often use a firing pin that is too short to project when depressed flush by the hammer. This type of firing pin, called an inertial firing pin, must be struck by a full fall of the hammer to provide the momentum
to move forward and strike the primer. If the hammer is down, resting on the firing pin, it is very unlikely that a blow to the rear will provide enough energy to the firing pin to detonate the primer. Most variants of the M1911
pistol use this type of firing pin.
Many firing pins are stamped from sheet steel, forming a rectangular cross-section rather than a round one. These will often have a cylindrical section at the front rather than a hemispherical one, and are fairly common in rimfire firearms. Sturm, Ruger
, for example, uses sheet metal firing pins in its 10/22 carbine
and Mark II pistol
.
High performance firing pins are often made from lighter materials than steel, such as titanium
. The lighter material increases the speed at which the firing pin travels, and reduces the lock time, or the time from trigger pull to the bullet leaving the barrel. See accurize for more information.
out of a round bar of metal, much larger in diameter than a firing pin, to provide the mass required to detonate the primer. Two-piece strikers generally consist of a firing pin attached to a heavier rear section—in essence a hammer attached to the base of a firing pin. Two-piece strikers are commonly found on bolt action rifles, while single-piece strikers are found on pistols, such as those made by Glock.
s to chemical oxygen generator
s.
Firearm
A firearm is a weapon that launches one, or many, projectile at high velocity through confined burning of a propellant. This subsonic burning process is technically known as deflagration, as opposed to supersonic combustion known as a detonation. In older firearms, the propellant was typically...
or explosive device e.g. an M14
M14 mine
The M14 mine is a U.S. small anti-personnel land mine first deployed circa 1955. The M14 mechanism uses a belleville spring to flip a firing pin downwards into a stab detonator when pressure is applied. Once deployed, the M14 is very difficult to detect because it is a minimum metal mine, i.e. most...
landmine or bomb
Bomb
A bomb is any of a range of explosive weapons that only rely on the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy...
fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
. Firing pins may take many forms, though the types used in landmines, bombs, grenade
Grenade
A grenade is a small explosive device that is projected a safe distance away by its user. Soldiers called grenadiers specialize in the use of grenades. The term hand grenade refers any grenade designed to be hand thrown. Grenade Launchers are firearms designed to fire explosive projectile grenades...
fuzes or other single-use devices generally have a sharpened point. In contrast, firing pins used in firearms usually have a small, rounded portion designed to strike the primer
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
of a cartridge
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
, detonating the priming compound, which then ignites the propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...
(in the case of firearms) or fires the detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
and booster
Explosive booster
An explosive booster acts as a bridge between a low energy explosive and a low sensitivity explosive such as TNT. It increases the explosive shockwave from an initiating explosive to the degree sufficient to detonate the secondary charge.Unlike C4 plastic explosive, not all explosives can be...
.
Firing pin vs. striker
A firing pin is a lightweight part, which serves to transfer energy from a spring-loaded hammerHammer (firearm)
thumb|150px|Hammer with an integral [[firing pin]] on a [[S&W Model 13]] revolver The hammer of a firearm was given its name for both resemblance and functional similarity to the common tool...
to the primer, while a striker is usually heavier, and is directly connected to the spring providing the energy to impact the primer. Striker mechanisms are generally simpler, since they combine the functions of hammer and firing pin in one.
The firing pin or striker is generally located in the bolt of a repeating firearm. Firearms that do not have bolts, such as revolver
Revolver
A revolver is a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing. The first revolver ever made was built by Elisha Collier in 1818. The percussion cap revolver was invented by Samuel Colt in 1836. This weapon became known as the Colt Paterson...
s and many types of single-shot
Single-shot
Single-shot firearms are firearms that hold only a single round of ammunition, and must be reloaded after each shot. The history of firearms began with single-shot designs, and many centuries passed before multi-shot designs became commonplace...
actions, generally have a very short firing pin in the frame, or else attached to the hammer itself. These types of firearms are almost never striker fired, as there is insufficient space to house a striker mechanism. Strikers are most commonly found in pistol
Pistol
When distinguished as a subset of handguns, a pistol is a handgun with a chamber that is integral with the barrel, as opposed to a revolver, wherein the chamber is separate from the barrel as a revolving cylinder. Typically, pistols have an effective range of about 100 feet.-History:The pistol...
s and bolt action firearms.
Firing pin construction
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
, with the end that strikes the primer rounded into a hemispherical shape and hardened. The rounded end ensures the primer is indented rather than pierced, as would happen if the firing pin were sharply pointed. Most firing pins have a spring to push them out of contact with the primer, and often will have an integrated passive safety mechanism, such as a block that prevents them from moving forward unless the trigger is depressed, or a transfer bar, also trigger actuated, that must be in place to allow the hammer to depress the firing pin. This safety is in addition to any manually operated safety or safeties that act to block the trigger or hammer.
Firearms that use long firing pins, such as pistols, will often use a firing pin that is too short to project when depressed flush by the hammer. This type of firing pin, called an inertial firing pin, must be struck by a full fall of the hammer to provide the momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
to move forward and strike the primer. If the hammer is down, resting on the firing pin, it is very unlikely that a blow to the rear will provide enough energy to the firing pin to detonate the primer. Most variants of the M1911
M1911
The M1911 is a single-action, semi-automatic, magazine-fed, and recoil-operated handgun chambered for the .45 ACP cartridge. John M. Browning designed the firearm which was the standard-issue side arm for the United States armed forces from 1911 to 1985. The M1911 is still carried by some U.S....
pistol use this type of firing pin.
Many firing pins are stamped from sheet steel, forming a rectangular cross-section rather than a round one. These will often have a cylindrical section at the front rather than a hemispherical one, and are fairly common in rimfire firearms. Sturm, Ruger
Sturm, Ruger
Sturm, Ruger & Company, Incorporated is a Southport, Connecticut-based firearm manufacturing company, better known by the shortened name Ruger. Sturm, Ruger produces bolt-action, semi-automatic, full-automatic, and single-shot rifles, shotguns, semi-automatic pistols, and single- and double-action...
, for example, uses sheet metal firing pins in its 10/22 carbine
Ruger 10/22
The Ruger 10/22 is a semi-automatic rimfire rifle chambered in .22 Long Rifle. It has a removable 10-round rotary magazine which allows the magazine to fit flush with the bottom of the stock. Higher capacity magazines are also available...
and Mark II pistol
Ruger MK II
The Ruger MK II is a rimfire single-action semi-automatic pistol chambered in .22 Long Rifle and manufactured by Sturm, Ruger & Company. Ruger rimfire pistols are some of the most popular handguns made, with over three million sold.-Models:...
.
High performance firing pins are often made from lighter materials than steel, such as titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
. The lighter material increases the speed at which the firing pin travels, and reduces the lock time, or the time from trigger pull to the bullet leaving the barrel. See accurize for more information.
Striker construction
Strikers are basically spring-loaded firing pins, generally of a one- or two-piece construction. In the one-piece striker, the striker is turned on a latheLathe
A lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...
out of a round bar of metal, much larger in diameter than a firing pin, to provide the mass required to detonate the primer. Two-piece strikers generally consist of a firing pin attached to a heavier rear section—in essence a hammer attached to the base of a firing pin. Two-piece strikers are commonly found on bolt action rifles, while single-piece strikers are found on pistols, such as those made by Glock.
Other uses
Mechanisms involving firing pins can be used also in other pyrotechnical systems, ranging from hand grenadeHand grenade
A hand grenade is any small bomb that can be thrown by hand. Hand grenades are classified into three categories, explosive grenades, chemical and gas grenades. Explosive grenades are the most commonly used in modern warfare, and are designed to detonate after impact or after a set amount of time...
s to chemical oxygen generator
Chemical oxygen generator
A chemical oxygen generator is a device releasing oxygen created by a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate. A promising group of oxygen sources are ozonides. The generators are usually ignited mechanically, by a firing pin, and the...
s.