# Firearm **A gun designed to be carried and operated by a single person.** The term *firearm* is typically used to refer to guns that are intended for carry and use by an individual. This is in contrast with the more general term *gun* which describes any ranged weapon that uses a barrel to launch a projectile. Modern firearms are described by their [[calibre]] or the [[cartridge]] they fire, the type of [[action]] used, and the [[Firearm Types|usage or configuration]] of the weapon. In the following, only modern firearms are discussed. ## Components > [!Pistol without a hammer]+ > ![[FirearmComponents1.svg|550]] > ![[FirearmComponents3.svg|550]] > *[[Glock|Glock 17]]; a semi-automatic pistol without a hammer shown with slide back* > [!Pistol with an external hammer]+ > ![[FirearmComponents2.svg|550]] > *[[Desert Eagle]]; a pistol with an external hammer and safety lever* > [!Submachine gun with assault rifle style controls]+ > ![[FirearmComponents4.svg]] > *[[MPX]]; a submachine gun with a control layout similar to an AR-15* > [!Assault rifle bolt carrier group]+ > ![[FirearmComponents5.svg|500]] > *[[G36]]; parts of the internals of an assault rifle with a central charging handle on top* *** ### Barrel > [!Barrel]+ > A *barrel* is the tube through which the projectile is propelled through. The front end of a barrel is known as the *muzzle* and the rear end may be referred to as the *breech* if, like in most modern firearms, the [[Firearm#^175cb3|chamber]] is integral to a barrel. The interior of the barrel is known as the *bore*. > > Most modern firearms except [[Firearm Types#Shotgun|shotguns]] have a rifled barrel. However, shotguns primarily shooting slugs may also have a rifled barrel. > > ![[FirearmBarrel.svg]] > *Barrels of a [[Glock|Glock 17]] and a [[G36]]; note the tilting barrel of the Glock* *** ### Bolt >[!Bolt]+ > A *bolt* is the component that blocks the breech during firing. It reciprocates during operation, loads [[Cartridge|cartridges]] from the [[Firearm#Magazine|magazine]], and extracts fired cartridges. > > The [[Firearm#Firing pin|firing pin]] and [[Firearm#Extractor and ejector|extractor]] are typically part of the bolt. > > The bolt may also be contained in a *bolt carrier*, which receives the impulse that cycles the firearm. Together they are referred to as the *bolt carrier group*. > > ![[FirearmBolt.svg|550]] > *A [[G36]] rotating bolt and its location within the weapon; note that the bolt is contained within the bolt carrier* > > A *rotating bolt* is a bolt which rotates locking lugs into recesses in either the [[Firearm#Receiver|receiver]] or the barrel to lock the breech closed during firing. Rotation is achieved by a radial projection, often called a *cam*, guided by a spiral track. Note that [[Action#Rotating bolt|rotating bolt]] also refers to a type of bolt action in which the operator must rotate the bolt handle. > > A *telescoping bolt* is a bolt which telescopes over the breech. As bolts require a minimum amount of mass for reliable operation, telescoping the bolt over part of the breech allows for shorter weapon designs. > > Firearms with a bolt can also be distinguished as either *closed bolt* or *open bolt*. > #### Closed bolt If a firearm fires from a *closed bolt* then, when it is ready to fire, the bolt and other moving parts are in their *forward positions* and *a round sits in the chamber*. When the trigger is pulled, the round is fired and the bolt is sent to the rear where the spent cartridge is extracted. The bolt then travels forward and chambers a new round before closing. ##### Advantages - Cleaner operation; the bolt mainly stays closed and prevents entry of contaminants - Further reduced noise in a suppressed weapon - Higher accuracy semi-automatic shots; no heavy moving parts prior to firing ##### Disadvantages - More complicated and expensive - Lower heat dissipation - Ability to fire with the magazine removed; the round in the chamber must be manually cleared #### Open bolt If a firearm fires from an *open bolt* then, when it is ready to fire, the bolt and other moving parts are held in their *rearward positions* and the *chamber is empty*. When the trigger is pulled, the bolt travels forward and chambers a new round which is immediately fired as the bolt closes. The bolt is then sent to the rear and held open. ##### Advantages - Fewer moving parts; the fixed firing pin strikes the [[Cartridge#Primer|primer]] by the force of the bolt closing - Higher passive heat dissipation ##### Disadvantages - Higher risk of accidental discharge by hard impact - Delayed firing after trigger pull - Less accurate semi-automatic shots; heavy parts have to move prior to firing - Higher risk of the introduction of contaminants ^3c9396 *** ### Chamber ^a990e9 > [!Chamber]+ > The *chamber* is the cavity into which the [[Cartridge|cartridge]] is inserted prior to being fired. > > In most modern firearms, the chamber is integral to the rear end of the barrel. By contrast, a revolver has multiple chambers in its cylinder with the barrel separate as a part of the frame. > > Inserting a round into the chamber is known as *chambering*. ^175cb3 *** ### Clip > [!Clip]+ > A *clip* is a device, typically stamped sheet metal, that stores multiple [[Cartridge|cartridge]] of ammunition together as a unit for loading into a firearm. There are three types: > - *stripper* clip - a clip placed into position above an open bolt, allowing the rounds to be pushed into the [[Firearm#Internal magazine|internal magazine]] and "stripped" from the clip. > - *en bloc* clip - a clip that is inserted into the internal magazine with the cartridges. > - *moon* clip - a ring-shaped clip designed for revolvers. > > ![[FirearmClips.svg|500]] > *Karabiner 98k stripper clip (left) and M1 Garand en bloc clip (right)* *** ### Charging handle > [!Charging handle]+ > A *charging handle*, also known as a cocking handle, is a device which can be used to "charge" or "cock" the weapon by pulling the [[Firearm#^3c9396|bolt]] to the rear thus readying the firing mechanism and, in a [[Firearm#Closed bolt|closed bolt firearm]], loading a new round from the [[Firearm#Magazine|magazine]]. > > Pulling the charging handle also *opens the breech* which extracts loaded [[Cartridge|cartridges]] and allows for the chamber to be checked and stoppages to be cleared. > > In a weapon which *holds the bolt open* after the last round, it can also be used to *release the bolt*. > > Charging handles may be *reciprocating* or *non-reciprocating*. Reciprocating charging handles are usually *integral to the bolt* or directly connected to it and provides the user with greater control over the bolt. However, reciprocating handles can cause injury while firing or cause a malfunction if the user accidently holds it while the weapon attempts to cycle. > > Most charging handles are located on one side of the firearm. In AR-15 style firearms, the charging handle is non-reciprocating, ambidextrous, and located at the back of the receiver. Some firearms, like the G36 and FAMAS, have central charging handles under their carrying handles which also allow for ambidextrous use. > > ![[FirearmChargingHandle.svg|500]] > *Charging handles (red) and bolt carrier groups (aquamarine) of an [[MPX]], an AR-15 style submachine gun, and a [[G36]], which has a central charging handle integral with the bolt carrier* *** ### Disconnector > [!Disconnector]+ > A *disconnector* is the part of the firing mechanism that "disconnects" the [[Firearm#Trigger|trigger]] from the firing mechanism after it is pulled. > > Its use is to ensure the firing mechanism is allowed to reset regardless of whether or not the operator is still applying pressure on the trigger. > > A disconnector functions by assuming control of the movement of either the [[Firearm#Sear|sear]] or the [[Firearm#Hammer|hammer]] until the firing mechanism has reset and the trigger is released. > > ![[FirearmDisconnector1.svg|450]] > *Disconnector (red) within the firing mechanism (aquamarine) of an [[M1911]]* > >[!Explanation]- > > As the trigger is pulled, the disconnector is pushed rearwards by the trigger which pushes the sear. The sear rests on a shelf at the bottom of the disconnector. > > > > After a round is fired, the slide travels backwards and begins resetting the firing mechanism. > > > > The top of the disconnector sits in a shallow hole in the slide and is pushed downwards as the slide travels backwards. In its downwards position, it is too low to continue to engage the sear and thus the sear can reset its position even if the trigger is still depressed. > > > *** > ![[FirearmDisconnector2.svg]] > *Disconnector, trigger, and hammer of an [[M4 carbine]]; the trigger is still fully depressed and the bolt is at the rear* > > [!Explanation]- > > The M4 carbine lacks a semi-automatic sear and its role is played by the front of the trigger instead. > > > > When the trigger is pressed, it releases the hammer and rotates the disconnector clockwise. > > > > After the round is fired, the bolt travels backwards and pushes the hammer which rotates anticlockwise and becomes caught by the disconnector as shown above. In this position the hammer is not controlled by the trigger at all. > > > > The disconnector stays rotated until the trigger is released which then allows the hammer to rotate clockwise the ready to fire position, where control of the hammer is reassumed to the trigger. *** ### Extractor and ejector > [!Extractor and ejector]+ > An *extractor* is the part that holds onto the [[Cartridge#Case|rim]] of spent cartridge casings and pulls them from the chamber as the [[Firearm#Bolt|bolt]] travels backwards. It resembles a hook and may be integral to the bolt. > > An *ejector* is the part that is used with an extractor and provides a *pushing force* opposite to the pull from the extractor to impart a torque onto the casing and ejecting it. It is either part of the [[Firearm#Receiver|receiver]] or bolt but may be a fixed or actuated protrusion or a simple ramp. > > ![[FirearmExtractorEjector.svg]] > *Ejector and extractor (red) within the bolt (aquamarine) of a [[G36]]; when the bolt reaches the rear, the ejector is forced forward and applies a torque to the casing (blue)* > *** ### Firing pin > [!Firing pin]+ > A *firing pin* is the component of the firing mechanism which strikes the [[Cartridge|primer]] and fires the round. A typical firing pin is a rod with a *rounded tip* which strikes and crushes but not puncture the primer. > > A firing pin may be moved by a hammer, a compressed spring, or by the [[Firearm#Closed bolt|bolt]] it is fixed in. > - *Spring-loaded* - a firing pin held in place by a return spring and struck by a hammer. > - *Striker* - a firing pin actuated by a spring which is compressed prior to firing. > - *Floating* - a firing pin that is free to slide within the bolt and is struck by a hammer and returned to position by inertia. > - *Fixed* - a firing pin that is fixed into the bolt and strikes the primer by the force of the bolt closing. > > ![[FirearmFiringPin.svg]] > *Firing pins (red) within the firing mechanisms (aquamarine) of an [[M1911]] and a [[Glock|Glock 17]]; the M1911 has a spring-loaded firing pin and the Glock 17 has a striker* ^3592cb *** ### Hammer ^efd6e5 > [!Hammer]+ > The *hammer* is the component of the firing mechanism that strikes the firing pin. It is a metal piece that *pivots* around a point and is moved by a spring held either in tension or compression. > > The hammer features a *notch* in which the [[Firearm#Sear|sear]] rests and holds the hammer in place. When the [[Firearm#Trigger|trigger]] is pulled, the sear moves out of the notch and releases the hammer. > > ![[FirearmHammer1.svg|450]] > *Hammer (red) within the firing mechanism (aquamarine) of an [[M1911]] pistol* > *** > ![[FirearmHammer2.svg]] > *Hammer (red) within the firing mechanism (aquamarine) of a [[G36]] assault rifle* ^ecad38 *** ### Magazine > [!Magazine]+ > A *magazine* is a device that stores ammunition and pushes [[Cartridge|cartridges]] into a position where they can be loaded into the [[Firearm#Chamber|chamber]] by the [[action]]. > > All magazines push rounds with a *follower* but the type of magazine dictates the mechanism that drives the follower. In magazines involving a rotating mechanism, the follower may be a *rotor* instead. > > In firearms with *last round hold open*, the follower also engages a slide stop or bolt catch when the magazine is empty which holds the slide or bolt back. > > Most types of magazines, except tubular and internal magazines, are *detachable*. Firearms using detachable magazines have a *magazine catch* or *magazine release* which locks the magazine in place. It is also used to release the magazine. > > ![[FirearmMagazine.svg|400]] > *Detachable box magazines of a [[Glock|Glock 17]] and a [[G36]], showing their typical form in a pistol and an assault rifle* ^59a18a #### Tubular A *tubular* magazine stores cartridges *end-to-end in a tube* and is commonly found in [[Action#Pump-action|pump-action]] [[Firearm#Shotgun|shotguns]]. The follower of a tubular magazine is driven by a spring compressed by the insertion of cartridges. Cartridges with *pointed* bullets stored in tubular magazines may cause problems as the point of a bullet may impact the primer of the cartridge in front of it, thus causing it to fire. ![[FirearmTubularMagazine.svg]] *Magazine tube of a [[SPAS-12]]* #### Box A *box* magazine stores cartridges in either a single column, *single-stack*, or two staggered columns, *double-stack*. In a firearm with last round hold open, the follower also engages the *slide stop* or *bolt catch* and holds the slide or bolt open. ![[FirearmSingleDoubleStackMagazine.svg|200]] *An [[M1911]] single-stack box magazine (left) and a [[Glock]] double-stack box magazine (right)* ##### Internal magazine An *internal magazine* is integral to the firearm and is most commonly found in [[Action|bolt-action]] rifles. They can be loaded by stripper [[Firearm#Clip|clips]] or en bloc clips. The follower of an internal magazine is typically part of a mechanism cycled by the action. ![[FirearmInternalMagazine.svg]] *Internal magazine of an M1 Garand loaded with an en bloc [[Firearm#Clip|clip]]; in essence the internal magazine is the cavity into which the clip is placed* ##### Detachable box magazine A *detachable box magazine* is a separate self-contained box magazine which is attached to the firearm through the *magazine well*. Detachable box magazines contain the follower and the spring that drives it. The spring is compressed when the magazine is loaded and drives the follower which pushes the cartridges. ![[STANAGMagazine.svg]] *A STANAG magazine* #### Drum A *drum* magazine stores cartridges in a *rotating spiral* within a *cylindrical container* - a drum. The cartridges are stored parallel to the axis of rotation and is pushed by a follower or rotor driven by a *wound spring*. Cartridges exit the magazine through a vertical column. Though drums allow for more rounds to be stored more effectively than box magazines, they are *heavier and more complex* as a result and the internal mechanism is *noisy* when the user or carrier is in motion. Drum magazines may use a *follower assembly* which consists of a series of dummy cartridges that ensure that rounds exit the magazine correctly. Most firearms that can use drum magazines are also compatible with box magazines. ![[FirearmDrumMagazine.svg]] *An example drum magazine; the center of the follower assembly is a spindle connected to the magazine spring and each dummy round is connected to each other* #### Helical A *helical* magazine stores cartridges in a *helix* within a long cylinder. Cartridges are pushed against a helical spiral by a rotating rotor-like component called a *separator* which is driven by a *torsion spring*. Helical magazines may include a follower which is also moved by the separator. ![[FirearmHelicalMagazine.svg]] *Helical magazine of a PP-19 Bizon* *** ### Pistol grip > [!Pistol grip]+ > A *pistol grip* is a type of grip designed to be reminiscent of the grip of a [[Firearm Types#Pistols|pistol]]. Pistol grips protrude from the firearm at a somewhat, though not completely, vertical angle which allows for a *more ergonomic grip* than a horizontal grip, a part of the receiver, or the [[Firearm#Stock|stock]] could provide. > > Pistol grips are placed behind the [[Firearm#Trigger|trigger]] and allow for several other controls to be placed on the firearm such that they can be operated *without removing the palm* from the grip. > > ![[FirearmPistolGrip.svg|500]] > *Pistol grips of an [[MPX]] and a [[G36]]; note that the G36 pistol grip part in actuality includes the trigger guard and magazine catch mechanism* *** ### Receiver ^9e592b > [!Receiver]+ > The *receiver* is the part that houses most of the internal components involved in the [[action]] of the firearm. Additionally, it is the part that *receives* the remaining external components of the firearm, such as the [[Firearm#Barrel|barrel]] and the [[Firearm#Stock|stock]]. > > In a [[Firearm#Pistol|pistol]], the part that acts as the receiver is referred to as the *frame* instead. > > ![[FirearmReceiver.svg|500]] > *Receivers of an [[MPX]] and a [[G36]]; the MPX, being an AR-15 style submachine gun, has a two-part receiver* ^29db41 *** ### Safety and selector switch > [!Safety switch]+ > A *safety switch* is the mechanism which prevents the firing of a firearm when engaged. Specifically, it is a *manual* or *external* safety intended to be enabled by the user when not firing. > > Safety switches either physically block the [[Firearm#Trigger|trigger]] from moving, disconnect the trigger from the firing mechanism, or block the [[Firearm#Hammer|hammer]] or [[Firearm#Firing pin|firing pin]] from moving. > > Safety switches exist in various forms, such as in the form of a push block, push button, or a lever. > > ![[FirearmSafetySwitch.svg|500]] > *Safety lever of a [[Desert Eagle]]* > [!Selector switch]+ > A *selector switch* is the mechanism which allows for the changing of the firing modes of a selective fire weapon. Often, the selector switch also integrates the *safety switch*. > > Some selective fire weapons may lack such a switch, with the role fulfilled by a [[Firearm#Trigger|progressive trigger]] instead. > > In general, the selector switch blocks and allows certain parts of the firing mechanism to move, such as a [[Firearm#Disconnector|disconnector]] and [[Firearm#Sear|sear]]/auto sear, to allow for the selected firing mode whilst prohibiting others. > - In *burst fire*, the selector switch engages a *cam mechanism* and an *auto sear* that automatically releases the cocked [[Firearm#Hammer|hammer]] for each round of the burst whilst the trigger is pulled. > - In *automatic fire*, the selector switch engages just an auto sear which automatically releases the cocked hammer as long as the trigger is pulled. > > ![[FirearmSelectorSwitch1.svg|500]] > *Selector levers of an [[MP5]] and an [[MPX]], showing their styles on Heckler & Koch firearms and on AR-15 style firearms respectively* ^f711c4 #### Example > [!M4 carbine four way selector switch]+ > On AR-15 style firearms, the general form of the selector switch with integrated safety is the same. > > To properly explain how the selector switch found on the [[M4 carbine]] works, the following components require some explanation. > - *Selector switch* - on AR-15 style firearms, the selector switch on the outside is directly connected to a cylinder with slots that allow or prohibit the movement of the trigger and disconnectors. > - *Auto [[Firearm#Sear|sear]]* - from the right side view, it is rotated anticlockwise by its spring after the [[Firearm#Bolt|bolt]] travels rearward and it is rotated clockwise by the forward movement of the bolt. > - [[Firearm#Trigger|Trigger]] - the trigger in the M4 also acts as the sear, and prohibits the hammer from moving if not pulled. > - *Burst disconnector* and [[Firearm#Disconnector|disconnector]] - the two disconnectors are placed adjacent to each other in a trench in the trigger. If unimpeded, the disconnectors are rotated with the trigger. > - [[Firearm#Hammer|Hammer]] - the hammer has three notches; at the tip for the auto sear, in the middle for the disconnectors, and at the axle end for the trigger. > - *Burst cam* - a cam engaged by the extra hook of the burst disconnector. It only rotates when the hammer rotates back. Of a group of three notches within its six, there is one deeper notch and two smaller ones. > > ![[M4SelectorSwitch0.svg|500]] > > In the following diagrams, the firing mechanism is depicted in the moment when a *round has been fired*, the *bolt is at the rear*, and the *trigger is still pulled*. This shows how the different firing modes react to the trigger still being depressed. > > ### Safe > While on safe, the trigger and disconnectors are *completely prevented* from rotating by the selector switch cylinder, as seen in the back view. > > ![[M4SelectorSwitch1.svg]] > > ### Semi-automatic > In semi-automatic mode, the trigger and disconnector are allowed to rotate but the burst disconnector and auto sear are not. > > After a round is fired, the hammer is pushed back by the bolt and its *middle notch is caught by the disconnector* that is rotated by the still pulled trigger. Note that in this position the hammer is rotated a little bit further anticlockwise than in the cocked position seen above. > > When the trigger is released, the disconnector is no longer rotated, the hammer rotates clockwise a small amount, and the control of the hammer is reassumed to the trigger. > > ![[M4SelectorSwitch2.svg]] > > ### Burst > In burst fire mode, the trigger, burst disconnector, and auto sear are allowed to rotate. > > After a round is fired, the hammer is pushed back by the bolt and *held by the auto sear*. With the bolt at the rear, the auto sear can rotate anticlockwise by its spring into the notch in the selector switch cylinder. The hammer is *automatically released* when the auto sear is *pushed forward by the bolt* as it returns to firing position. > > As the hammer rotates anticlockwise, the burst cam also rotates anticlockwise by one notch, causing the extra hook of the burst connector to move into the next notch. > > For the *first two rounds* of a complete burst, the notches are *not deep enough* for the burst disconnector to hook the middle notch of the hammer. Thus, the auto sear assumes full control of the hammer. > > After the *last round* of the burst is fired, the burst disconnector falls into the *deeper notch* of the burst cam and catches the hammer. The trigger must then be released to reassume control of the hammer from the burst disconnector. > > ![[M4SelectorSwitch3.svg]] > > ### Automatic > In automatic mode, the trigger and auto sear are allowed to rotate. Both disconnectors are blocked. > > After a round is fired, the hammer is pushed back by the bolt and *held by the auto sear*. With the bolt at the rear, the auto sear can rotate anticlockwise by its spring into the notch in the selector switch cylinder. The hammer is *automatically released* when the auto sear is *pushed forward by the bolt* as it returns to firing position. > > As long as the trigger is pulled, the auto sear assumes full control of the hammer and *automatically releases* the hammer as the bolt travels forward to its firing position. > > Once the trigger is released, it *directly blocks* the hammer from moving. > > ![[M4SelectorSwitch4.svg]] *** ### Sear > [!Sear] > The *sear* is the component of the firing mechanism which holds the [[Firearm#Hammer|hammer]], [[Firearm#Firing pin|striker]], or [[Firearm#Bolt|bolt]] in the ready to fire position until the [[Firearm#Trigger|trigger]] has been pulled. > > A [[Firearm#Disconnector|disconnector]] is often also used with a sear to disconnect it from the trigger after it is pulled such that the firing mechanism can reset regardless of trigger position. > > Sears are not present in all firearms and designs without them typically use part of the trigger as a sear. > > In a firearm with automatic fire capability there exists an *auto sear* as well as a normal sear. An auto sear allows for the holding and releasing of the hammer to be automatic, as long as the trigger is depressed. It is typically operated by the reciprocation of the bolt and its own spring. > > ![[FirearmSear1.svg|450]] > *Sear within the firing mechanism of an [[M1911]]* > *** > ![[FirearmSear2.svg]] > *Sear within the firing mechanism of a [[G36]]* > *** > ![[FirearmSear3.svg]] > *Auto sear, trigger (also acting as a sear), disconnector, and hammer of an [[M4 carbine]]; the trigger is still fully depressed and the bolt is at the rear* *** ### Slide >[!Slide] > The *slide* is the upper part of [[Firearm Types#Pistol|pistols]] which travels backwards due to recoil after a round is fired and returns forward to complete an operation cycle. Slides are returned to firing position by its spring. > > It effectively serves as the [[Firearm#Bolt|bolt carrier group]] and also contains the [[Firearm#Firing pin|firing pin]], [[Firearm#Extractor and ejector|extractor and ejector]], and typically also the [[Firearm#Barrel|barrel]]. The reciprocation of the slide resets the firing mechanism of the pistol, including by readying the [[Firearm#Hammer|hammer]] or striker, and chambers a new round from the [[Firearm#Magazine|magazine]]. > > Iron sights are fitted to the top of slides and some have integrated Picatinny rails for mounting other optical sights. > > The slide can be held at the back by a *slide stop*, which can be manually engaged or, as in most modern pistols, is engaged by the follower in the magazine after all rounds are fired. > > ![[FirearmSlide.svg|550]] > *Slide of a [[Glock|Glock 17]], shown in forward and held back positions with the slide stop (blue) disengaged and engaged* *** ### Stock ^de60e3 >[!Stock] > A *stock* is the part of the firearm which allows it to be braced by an operator in their shoulder, thus stabilising it during firing. > > In older long guns, the stock is a single piece extending from the rear of the weapon towards the underside of the [[Firearm#Barrel|barrel]], where is serves as a handguard. Single piece stocks also provide structural support for the weapon and contains the [[action]] and firing mechanism. > > In most modern firearms, the stock simply refers to the rear end of the traditional stock, as [[Firearm#Receiver|receivers]] and separate handguards replace its front parts instead. > > ![[FirearmStock.svg]] > *Extending stock of an [[MP5]] and folding stock of a [[SPAS-12]]* ^4d1a59 *** ### Trigger >[!Trigger] > A *trigger* is the part of the firing mechanism which is typically depressed by the index finger of the operator to discharge the firearm. Most triggers are in the form of a lever, descending into a protective loop called the *trigger guard*. > > Most triggers are *single-action* and only disengages the [[Firearm#Sear|sear]] which releases the [[Firearm#Hammer|hammer]] or [[Firearm#Firing pin|striker]]. Triggers in *double-action* designs are also involved in cocking the hammer. In some designs the trigger may also act as the sear. > > Some firearm designs may replace a [[Firearm#^f711c4|selector switch]] with a *progressive trigger* instead. Such triggers fires a single-shot when pulled lightly and fires automatically when fully depressed. > > ![[FirearmTrigger.svg|500]] > *Triggers and trigger guards of an [[MPX]] and a [[G36]]* ***