Trigger (weapon)

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Deduction for a straight pull lock
Pulling a trigger on a Makarov

The deduction ( English trigger referred to) both to actuate the trigger mechanism of the weapon protruding trigger blade when the entire exhaust system (including deduction group ) - the establishment of a firearm with which the finger movement over a lever mechanism triggers the shot triggering mechanism of the weapon.

Use of language

In the arms system, the term “deduction” is ambiguous. Both the operating lever - the trigger tongue - and the entire assembly group that triggers the shot - the trigger system or, technically, the trigger group - are referred to as the trigger.


Crossbow, 16th century

With early firearms, for example the crossbow , a simple lever mechanism was sufficient as a trigger, which released the pawl for the bowstring and bolt and thus triggered the shot. In the historical development of firearms, the influence of the trigger on the precision of a weapon was recognized early on, which led to the development of complex mechanical locks for cocking and releasing percussion weapons . Some of these locks already had a very high level of manufacturing accuracy and allowed correspondingly precise shots to be fired. With the development of modern cartridge ammunition and the development of semi-automatic and fully automatic weapons, the function of the locks was divided between the breech and its clamping device and the trigger. Thus, due to the design, the development of trigger groups was necessary for magazine-loaded weapons. The character of the locks used earlier was retained for the longest in revolvers, as these do not have a bolt and magazine. On military handguns with a trigger lever, the trigger can be changed from a fully automatic fire mode to a semi-automatic one, whereby the fully automatic fire mode can be limited sequentially to three to five shots. The latest weapon designs have electronic triggers of various designs, from simple electronic firing to electronic user identification with trigger lock.


Due to the long history of firearms and the large number of designs, the function of a trigger can only be explained using a selected example. This makes it clear that there is no such thing as “the trigger”.

The control of the not insignificant influences of the trigger on the shooting behavior and thus on the precision of the entire weapon is called trigger control . A trigger control exercised by the shooter requires a precisely and safely executed trigger or a trigger group in which all components are coordinated with one another. It is controversial which components belong exactly to the deduction group; from the trigger blade to the firing pin, or from the trigger blade to the striking piece, with or without striking spring. Every weapon designer or manufacturer has their own point of view on this issue.

The illustration shows the components of a trigger group up to the hammer using the example of the widely used Colt 1911 (Pistol cal .45 M1911A1), also known as the Colt Government Model. The preceding numbers in the text correspond to the numbers in the illustration.

The trigger (No. 23) on the Colt Government M1911A1
Basic components
23   Trigger with the so-called stirrup, which here acts as a trigger push rod.
19   Interrupter (disconnector), which prevents the hammer from being released if it is not locked.
18   Hahnrast (Sear), which locks the striking piece (hammer) in its rear (cocked) position by means of a breaker.
14   Striker / hammer, which transfers the energy of the tensioned striker spring and its own mass to the firing pin via additional components in the slide.
Advanced components
15   Striker / Hahn Pin (pin, hammer strut) that connects the striker to the striker spur.
16   Striker / Hahn spur (Hammer Strut), for transferring the striker energy to the striker.
12   Stopcock spring (Spring, Sear), for repositioning the stopcock.
09   Spring cap (Cap, Main Spring), to support the hammer spur.
10   Main Spring, energy storage for triggering the shot.
11   Spring bearing insert, lower spring bearing.
Fuse components
01   Safety wing (Safety, Thumb). The safety device operated with the thumb prevents the trigger from being pushed through by locking the stirrup (trigger pushrod) and at the same time blocks the bolt.
03   The grip safety (Safety, Grip) prevents accidental triggering of a shot when the weapon is not in hand by locking the cock notch.
- It is also possible to secure the loaded weapon against accidental activation of the trigger with the help of the so-called half-position notch of the hammer (half cock), another option for locking the hammer when the weapon is half-cocked. It also prevents the triggering of the shot if it slips when the cock is cocked.
- Another safety device, not shown, is the disconnector, in which a shot is not possible even if the breechblock is only slightly open.

Other firearms have similar or completely different trigger systems and trigger components. In the sporting weapon sector, for example, some of these components can be individually influenced and adjusted to the individual needs of the shooter.

Control element for triggering a shot

The trigger or trigger is the actual control element for triggering the shot. The trigger on small firearms and handguns is usually operated with the index finger; The thumb trigger is also used for heavier military weapons, for example for heavy machine guns, cannons or machine cannons. The majority of handguns have a pivot-mounted trigger (trigger blade). Some hand weapons z. B. Colt M1911 or Tokarew TT-33 are equipped with a linear-guided trigger. The thumb trigger (often called butterfly trigger because of its shape) is located between two handles. There are also simple lever triggers, for example on cannons, that are pulled back and simply released to fire the shot. With modern shoulder-supported small rocket launchers, only an electrical switch is operated. The possible designs are certainly as diverse as the fume cupboard designs themselves.

To make it easier to carry a handgun in a pocket of an item of clothing , a folding trigger is sometimes used. The trigger is folded away from the handle for storage. There is no trigger guard with this design. The ring trigger was also intended for pocket pistols.

With the Swiss Assault Rifle 57 , a trigger guard (winter trigger) that can be folded down next to the trigger and protrudes over the trigger guard can be used for shooting with mittens. It is also used when using rifle grenades when the weapon is unsupported, in order to avoid hand injuries caused by the strong recoil. Since there is a risk of an unintentional triggering of the shot when the winter trigger is folded down, it should only be folded down immediately before the shot is fired and swiveled in after the shot.

In weapons with a tail trigger, this is inserted in a horn-shaped projection at the bottom of the frame and protected by it. Revolvers with a tail trigger can only be fired as a "single action" weapon.

In order to shorten the trigger travel, a trigger stop is used on some weapons .

Trigger with fire selection function

Two-piece trigger an MG 34: E inzelfeuer above, D except fire below

With some weapons, a fire selection function is integrated in the trigger, with which the shooter can choose between single and continuous fire by operating the trigger differently.

With a two-part trigger, e.g. B. MG 34 , the weapon fires single shots when you pull the upper half of the trigger, while the lower half is used for continuous fire.

Some weapons, e.g. B. the Steyr AUG , use a trigger with two different pressure points. The weapon fires single fire when it reaches the first pressure point, continuous fire when it reaches the second pressure point.

Trigger guard

In the case of handguns, the trigger tongue is usually protected against contact - and thus against unintentional firing - by a trigger guard. This trigger guard can be part of the frame or the handle (see drawing above) or it can be attached.

The trigger guard is sized to fit a finger. For weapons that are intended for use in the cold, the trigger guard is larger so that the weapon can also be fired with thick gloves . With some weapons it can therefore be folded down or removed. Some weapons have a trigger guard that is so large that it encloses the entire hand and thus allows the shooter to operate the trigger with a mitt .

Some early pistols and revolvers have a finger guard attached to the bottom of the trigger guard. The middle finger is placed on this , which allows a more precise shot.

With lever action rifles, the trigger guard is an integral part of the repeating lever.

Trigger plate

Trigger plate visible in a cutaway model of a
percussion pistol

The trigger plate (also called trigger plate or tongue plate ) is a component of the trigger, which occurs mainly in weapons with a full stock . It is located above the trigger guard on the shaft and is usually made of hardened cast iron . There are different versions with different functions.

  • As a fitting , the trigger plate reinforces the connection with the shaft. With the screw nut for the cross screw, the trigger also holds the tail screw blade and thus the barrel on the shaft. An alternative or additional possibility of connection are wood screws that hold the trigger plate directly on the shaft. However, the strength of the connection with a cross screw is significantly greater than that of screws in the shaft.
  • In some designs, a vertical bumper plate limits the penetration of the ramrod .
  • Often it serves as a holder for the bearing for the pin , which allows the trigger to rotate.
  • The tongue protrudes through an elongated cut in the trigger plate. This incision gives the tongue the necessary guidance so that it does not sway to the side.
  • In some designs, the trigger guard is attached to the trigger plate by hanging it on one side.
  • In the case of weapons with a breech block, the trigger plate closes it from below with a screw.

Trigger options

Direct trigger (also shotgun trigger)

Here the finger force is transmitted to the impact device without delay; the trigger weight must be overcome at the beginning. All mechanical transmission paths should be polished in order to keep the applied force as low as possible. A bad trigger mechanism "creeps", i. H. the trigger moves back a little before the shot is released and / or “hooks”. A different pressure on the trigger is necessary in order to trigger the shot.

Pressure point trigger

In contrast to the direct trigger, with the pressure point trigger the finger force is not immediately transferred to the striking device. First the first stage weight has to be overcome and the trigger pulled back a short first stage to the pressure point. Then the higher pressure point weight has to be overcome.

Set trigger

These triggers transmit their power indirectly, which means that the necessary trigger weight is reduced. With the set trigger, a spring is pretensioned in the trigger by "piercing", which is then relaxed by only lightly pressing the trigger. The energy of the pretensioned trigger spring in turn triggers the firing pin. See also engraver .

Anti stress deduction

An anti-stress trigger is a trigger on handguns that is intended to prevent accidental firing in stressful situations, since people - here the gun bearer - tend to cramp their hands in such situations and thus unintentionally apply high pressure on the trigger even when the gun is drawn exercise. In addition, the finger muscles can also tremble.

There are various approaches to preventing a shot from being released unintentionally in standby situations and possibly leading to serious or even fatal injuries:

Anti stress deduction

The Walther company uses a trigger with which a high trigger weight has to be overcome for the first shot. The trigger weight is reduced for subsequent shots (see Single Action ), but the path to be covered by the trigger is very long. Shaky fingers don't move that far. This construction principle is generally considered to be inferior to the partially pre-tensioned DAO systems in terms of the intended gain in safety and has not been able to prevail against them due to other design-related disadvantages.

Partially preloaded DAO

The advanced safety trigger concept for modern self-loading pistols is represented by the various partially pre-tensioned DAO systems. The best-known developer and market leader here is the Glock company with the so-called Safe Action System (see below, trigger systems).

Trigger systems

SA - single action

Single action trigger

The single-action trigger, also known as the direct trigger, is the simplest trigger system. Here only the already cocked firing pin is triggered without moving other mechanical parts such as the drum of the revolver . Before the next shot, the hammer must always be re-cocked (by hand or by the weapon system).

This is the oldest deduction system already Matchlock - flintlock - and percussion weapons and the first Colt revolvers and rifles for cartridge ammunition pure single-action weapons were. This is where the gun position at belt level, known from Western films, comes about, in which the edge of the hand of the second hand hits the hammer from above - this cocked the hammer while the index finger of the other hand held the trigger, which allowed rapid firing sequences.

The single-action trigger was initially used for self-loading pistols. It either triggered the firing pin or, on most pistols, a hammer. These constructions were originally intended to be carried with the cock cocked and the safety activated, which raised concerns among many users.

DA - double action

Double-action trigger on a Taurus PT92

The double-action trigger ("double" for two triggered processes), also known as DA / SA (double action / single action) or cocking trigger, is a further development of the single-action trigger. By operating (pulling) the trigger, the hammer is cocked until the shot is released. It is not necessary to tension the tap beforehand, but it can be done manually. With revolvers, the drum is also rotated further. With pistols, each additional shot is triggered according to the single-action trigger.

In 1908, Alois Tomiska's “Little Tom” featured the first double-action trigger of a self-loading pistol, which made it possible to carry the weapon ready to fire with the hammer relaxed. If the Czech Tomiska had not yet achieved commercial success, this principle became known with the Walther PP from 1929. Today it is common on most pistols. The disadvantage of this system is the significantly higher trigger resistance when the first shot is fired (compared to a single-action system) and the fact that the trigger resistance between the first shot and the subsequent shots differs significantly, which has a negative impact on the target (the shot precision).

DAO - Double Action Only

Smith & Wesson Model 642 Ladysmith with double-action-only trigger

The Double Action Only system (DAO), or clamping trigger is the tensioning and knocking off of the tap according to the previous Einrepetieren a cartridge into the cartridge chamber only possible by actuating the double action trigger system. One advantage of the DAO design is the possibility of being able to use the weapon without cocking and without any further safety actuation, as well as the constant trigger resistance with every shot.

Early examples of this are the Mariette bundle revolver (1836) and the Adams model 1851 revolver, both percussion weapons .

Between 1886 and 1937, the Smith & Wesson company manufactured so-called "Hammerless Model" drop barrel revolvers in calibers between .42 and .44, which were fitted with a ball safety device. The next variant of S&W DAO revolvers were the “Centennial Model 40” and “Model 42 Airweight” revolvers with a swing-out drum and a ball safety device, manufactured from 1952 to 1974. The Model 42 "Centennial Airweight" was initially made with a frame and drum made of an aluminum alloy, later models had a steel drum. The Model 40 was made of steel.

Partially preloaded DAO systems

Partially pre-tensioning system on a Glock 19

The partially preloaded DAO systems represent the state of the art for utility pistols. With a partially preloaded DAO trigger system, the mainspring is only partially preloaded when the slide moves back. Such a partially cocked weapon - usually a pistol - is now fully cocked only when the trigger is actuated at the moment the shot is fired and the shot is then immediately released, i.e. the spring is partially relaxed again. The trigger system therefore immediately reverts to the safe, partially pre-tensioned state at the moment the shot is fired. This functional principle results in several desirable properties for weapon control:

  • To overcome the remaining spring tension path when firing a shot, less effort is required by the finger triggering the shot. The trigger resistance is as low for the shooter with the first - possibly decisive - shot as with the subsequent shots, which significantly improves the accuracy (shot precision).
  • Due to the design, the partially pre-cocked system can only be set into a fully cocked and thus a shot-releasing state by pulling the trigger. Safety failures, such as those that can occur due to the unintentional release of the firing pin in fully cocked systems, are excluded with partially prestressed systems.
  • Unintentional firing due to manual safety devices, release levers and trigger blades that have to be operated under stress at the same time are eliminated here, since the trigger blade alone has to be actuated and, in addition, a split trigger blade design makes it difficult to trigger by foreign bodies instead of the finger.

The principle of the partially pre-tensioned DAO is implemented through the use of the force available when the slide runs back, regardless of whether it is built up by firing a shot or brought in by the gun operator by pulling the slide back during loading (repeating). Due to this construction principle, the weapon can always be used safely and still in the highest state of readiness. Incorrect or operating delays due to the actuation of further safety elements required in other systems are ruled out in the case of the stress-laden shot firing with the partially pre-tensioned system.

With modern self-loading pistols, the partially pre-cocked trigger systems dominate the market today, albeit under different names.

  • Glock , the market leader in the utility pistol market and developer of this trigger type, focuses on the safety aspect of the partially pre-tensioned system under the name "Safe Action". The partially pre-cocked Glock pistol cannot be accidentally triggered by accidentally activating a safety device or by dropping the weapon. With these systems only internal fuses are used, which are only released by actuating the trigger. However, the Glock trigger system is not a DAO system, but a single-action-only system, which is partially preloaded when loaded; the knocked off weapon (e.g. after a failed ignition) cannot be (pr) cocked via the trigger. The (pre-) cocking of a Glock pistol can only be done by repeating the slide (Heckler & Koch uses the same principle in the pistols of the SFP9 (VP9) series; Walther P99 / PPQ, however, is different; here is the cocking of the knocked off Weapon possible via the (DA) trigger).
  • Glock, on the other hand, describes two different, reinforced trigger springs for Glock pistols as the New York trigger , which were first installed when the New York City police switched from revolvers to Glock 19 self-loading pistols instead of the usual Glock trigger spring. This means that one of the design disadvantages of the revolver was "artificially" transferred to the pistol with the significantly higher trigger resistance, which does not promote precision; This measure made it much easier for the police officers who had been trained and equipped with revolvers for many years to get used to the pistol. The New York trigger is not an “anti-stress trigger” in the sense described above. However, it offers the possibility of offering gun carriers who have to alternately handle revolvers and pistols with a constant trigger resistance, which is certainly beneficial in a stressful situation.
  • The company Walther describes her teilvorzuspannenden systems as Quick Action Trigger . This trigger system is used in the Walther P99 version P99 QA .
  • Heckler & Koch LEM (Law Enforcement Modification), also known as CDA (Combat Defense Action).
  • The Steyr Mannlicher variant, the partially pre-tensioned Reset Action System , is currently being installed in the Steyr M-A1 and S-A1 pistols .
  • The SIG-Sauer GmbH offers its version under the name Double Action Kellermann / DAK to, installed in several models. With the DAK system, too, the weapon is always partially pre-cocked with a constant trigger weight, similar to the Glock's safe-action system.


  • Friedhelm Kersting, Helmut Kinsky, Claus-Henning Strube: The hunter and his weapons. Weapons, ammunition, optics - function and handling. 3rd completely revised and expanded edition. Parey-Zeitschriften-Verlag, Singhofen 2000, ISBN 3-89715-507-9 ( textbook Jägerprüfung 4).

Individual evidence

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