100-449: The SIG Pro is a series of semi-automatic pistols manufactured by SIG Sauer in Exeter, New Hampshire . It became the first polymer -frame handgun from SIG Sauer and one of the first pistols to feature a built-in universal accessory rail and interchangeable grips . Offerings in the series are chambered in .40 S&W , .357 SIG , or 9×19mm Parabellum . As of March 2020, only
200-529: A Picatinny rail , and a trigger guard that is visibly different than the first generation variants. The design was selected in 2002 as a new service pistol for French police , intended to have a 20-year service life (until 2022), hence the model number. Semi-automatic pistol A semi-automatic pistol (also called a self-loading pistol , autopistol , or autoloading pistol ) is a handgun that automatically ejects and loads cartridges in its chamber after every shot fired. Only one round of ammunition
300-474: A decocker and without a manual safety , unless noted otherwise. These offerings feature a proprietary SIG accessory rail. It was originally developed as a .40 S&W caliber service pistol and introduced in June 1998, followed shortly by a version in .357 SIG . About a year later, a 9×19mm Parabellum variant was introduced and entered production in response to demand for the type. These offerings feature
400-420: A punch / chisel , which then relays the hammer impulse by moving forward rapidly along its longitudinal axis. A striker is essentially a firing pin directly loaded to a spring, eliminating the need to be struck by a separate hammer. The firing pin/striker then collides into the cartridge primer positioned ahead of it, which contains shock-sensitive compounds (e.g., lead styphnate ) that sparks to ignite
500-411: A quicker initiation of fire, but compromised by having a longer, heavier trigger pull, which can affect accuracy compared to the lighter, shorter trigger pull of a single-action fire. In a DA/SA semi-automatic pistol , the trigger mechanism functions identically to that of a DA revolver. However, this is combined with the ability of the pistol slide to automatically cock the hammer when firing. Thus,
600-436: A "buffer zone" that prevents the shooter from "jerking the trigger", allowing the remnant pressing force from the finger to be dampened via a "follow-through" motion. Although a perceivable overtravel can be felt as adding to the "creep" of the trigger break, it is not always considered a bad thing by some shooters. An overtravel stop will arrest the motion of the trigger blade and prevent excessive movement. When user releases
700-505: A "fully automatic" or machine pistol, which continues to fire as long as the trigger is held or until all rounds have been fired. The Mauser M712 Schnellfeuer (German for "rapid fire"), a modified Mauser C96 pistol, is a notable example of a true machine pistol. While both types of weapons operate on the same principles, fully automatic weapons must be built more ruggedly to accommodate the heat and stress caused by rapid firing, and it can be difficult (and illegal in most countries) to convert
800-428: A "semi-automatic pistol" or a "self-loading pistol" usually all imply a semi-automatic handgun that is fed by a removable magazine, which discharges one round for each trigger pull. Semi-automatic pistols use one firing chamber that remains fixed in a constant linear position relative to the gun barrel. In contrast, although double-action revolvers can also be fired semi-automatically, their rounds are not fired from
900-500: A cartridge in one continuous motion. Each pull of the trigger on a DAO semi-automatic pistol requires the same amount of pressure. The Kel-Tec P-11 is an example of a DAO action. DAO semi-automatic pistols are most generally recommended only in the smaller, self-defense, concealable pistols, rather than in target or hunting pistols. A notable exception is the Glock range of pistols, which optimize preset triggers (similar to DAO), but
1000-477: A cartridge or loading the chamber, the hammer or striker will rest in a partially cocked position. The trigger serves the function of completing the cocking cycle and then releasing the striker or hammer. While technically two actions, it differs from a double-action trigger in that the trigger is not capable of fully cocking the striker or hammer. It differs from single-action in that if the striker or hammer were to release, it would generally not be capable of igniting
1100-435: A degree of safety in the field compared to having a conventional, very light trigger. There are two types: single set and double set. Set triggers are most likely to be seen on customized weapons and competition rifles where a light trigger pull is beneficial to accuracy. A single set trigger is usually one trigger that may be fired with a conventional amount of trigger pull weight or may be "set" – usually by pushing forward on
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#17328014230861200-424: A heavier weight and little or no discernible movement. A perceivably slow trigger break is often referred to as a "creep", and frequently described as an unfavorable feature. The trigger overtravel happens immediately after the break and is typically a short distance and can be considered an inertially accelerated motion caused by the residual push of the finger coupled with the sudden decrease in resistance after
1300-651: A machine pistol, in contrast, this can be accomplished by blowback , or, less commonly, by gas operation , harnessing gases produced when the gun is fired. The Desert Eagle is a rare example of a semi-automatic pistol that siphons off some of the gases instead of relying on short recoil operation. A revolver , which uses multiple chambers and a single barrel, and a derringer , which uses multiple chambers and multiple barrels, also fire one round per trigger pull, but achieve this in different ways and as such are not classified as being semi-automatic. A semi-automatic pistol will fire only one shot per trigger pull, in contrast to
1400-467: A manual safety that additionally may serve to decock the hammer. Some have a facility (generally a lever or button) to safely lower the hammer. As a disadvantage, these controls are often intermingled with other controls such as slide releases, magazine releases, take-down levers, takedown lever lock buttons, loaded chamber indicators, barrel tip-up levers, etc. These variables become confusing and require more complicated manuals-of-arms. One other disadvantage
1500-527: A police pistol. These weapons also generally lack any type of external safety. DAO is common among police agencies and for small, personal protection firearms. The primary drawback is that the additional trigger pull weight and travel required for each shot reduces accuracy. Pre-set triggers offer a balance of pull weight, trigger travel, safety, and consistency. Glock popularized this trigger in modern pistols and many other manufacturers have released pre-set striker products of their own. The primary disadvantage
1600-473: A removable box magazine to provide ammunition, which is usually inserted into the grip. However, some pistols are based on receiver -style designs similar to existing semi-automatic rifles , and thus have the magazine inserted separately from the grip. The language surrounding "automatic", "semi-automatic", "self-loading", etc., often causes confusion due to differences in technical usage between different countries and differences in popular usage. For example,
1700-488: A result an external safety is sometimes employed. Double-action triggers provide the ability to fire the gun whether the hammer is cocked or uncocked. This feature is desirable for military, police, or self-defense pistols. The primary disadvantage of any double-action trigger is the extra length the trigger must be pulled and the extra weight required to overcome the spring tension of the hammer or striker. DA/SA pistols are versatile mechanisms. These firearms generally have
1800-540: A screw-on wooden stock, the C-93 served well as a small pistol carbine . In 1896, Paul Mauser introduced the first model of his Mauser "Broomhandle" semi-automatic pistol, the C96 . This was the first mass-produced and commercially successful pistol to have a large-capacity, staggered-column magazine holding 10 or 20 rounds. Its original cartridge was called 7.63 mm Mauser , which was more powerful but otherwise identical to
1900-461: A semi-automatic pistol into a fully automatic mode of fire. A selective-fire action pistol, though, can be converted back and forth by means of a switch, and often includes a burst mode , typically for a three-round burst with each trigger pull. Selective-fire weapons are generally used by specialized law enforcement and security personnel such as SWAT teams, hostage rescue teams, anti-terrorist units, or government bodyguards for heads of state. In
2000-412: A single chamber, but rather are fired from each of the chambers that are rotated into linear alignment with the barrel's position in turn just prior for each shot fired. Typically, the first round is manually loaded into the chamber by pulling back and releasing the slide mechanism. After the trigger is pulled and the round is fired, the recoil operation of the handgun automatically extracts and ejects
2100-496: A single-action mechanism altogether, more commonly DAO revolvers are modifications of existing DA/SA models, with identical internals, only with access to the hammer prevented, either by covering it with a shroud or by removing the thumb spur. In both cases, the goal is to prevent the possible snagging of the hammer spur on clothing or holster. Due to the imposed limitation in accuracy, the majority of DAO revolvers have been short-barrel, close-range "snub" weapons, where rapidity of draw
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#17328014230862200-404: A single-stage or two-stage trigger by adjusting the takeup. Setting the takeup travel (also known as the first stage) to near zero essentially makes the trigger a single-stage trigger. Some single-stage triggers (e.g., Glock Safe Action trigger, Savage AccuTrigger ) have an integral safety with a noticeable spring resistance that can functionally mimic a two-stage trigger. The trigger break
2300-401: A spring) the hammer/striker, rotating a revolver 's cylinder , deactivating internal safeties , transitioning between different firing modes (see progressive trigger ), or reducing the pull weight (see set trigger ). A single-action (SA) trigger is the earliest and mechanically simplest of trigger types. It is called "single-action" because it performs the single function of releasing
2400-415: A trigger pull to both cock and trip the hammer/striker for every single shot, unlike a DA/SA, which only requires a double-action trigger pull for the first shot (or a typical DA/SA revolver, which can fire single action any time the user wishes but uses double-action as a default). This means that there is no single-action function for any shot, and the hammer or striker always rests in the down position until
2500-661: A very heavy slide and stiff spring, making them bulky, heavy, and difficult to operate. A somewhat commercially successful blowback pistol design in the more powerful calibers was produced; the Spanish Astra 400 in 9 mm Largo and the similar Astra 600 in 9 mm Parabellum. U.S. manufacturer Hi-Point also produces a line of blowback-operated pistols in several calibers, including 9 mm and .45 ACP. Virtually all other service-caliber pistols are locked-breech designs After Hiram Maxim introduced his recoil-powered machine gun in 1883, several gunsmiths set out to apply
2600-426: A way to catch the hammer on release; while the other two have three-position safety selectors and a way to capture the hammer on release. In these triggers, the third position activates the pull and release mode, while the center selector position causes the trigger to only drop the hammer when pulled. A set trigger allows a shooter to have a greatly reduced trigger pull (the resistance of the trigger) while maintaining
2700-445: Is a trigger that must perform the double function of both cocking and releasing the hammer/striker. Such trigger design either has no internal sear mechanism capable of holding the hammer/striker in a still position (so cocking and releasing have to happen in one uninterrupted sequence), or has the whole hammer shrouded and/or with the thumb spur machined off, preventing the user from manipulating it separately. This design requires
2800-504: Is also known as traditional double-action (TDA), as the vast majority of modern "double-action" handguns (both revolvers and semi-automatic pistols ) use this type of trigger instead of "double-action only" (DAO). In simple terms, "double-action" refers to a trigger mechanism that both cocks the hammer and then releases the sear, thus performing two "acts", although it is supposed to describe doing both strictly with one trigger pull only. However, in practice most double-action guns feature
2900-417: Is an example of this style of action. A common mode of carry for DA semi-automatic pistols is with the magazine full, a round chambered, and the gun holstered and uncocked with the external safety unengaged or off. The Taurus PT145 is an example of a DA/SA weapon, as it has no decocker and thus has its striker primed from the moment of chambering and only enters double-action mode if a round fails to fire upon
3000-407: Is condition 1, popularly known as cocked and locked. Condition 1 (a term popularized by Jeff Cooper ) refers to having the magazine full, a round chambered, the hammer fully cocked, and the thumb safety engaged or on, at least for right-handed users. For many single-action, semi-automatic pistols, this procedure works well only for right-handed users, as the thumb safety is located on the left side of
3100-412: Is essential and limited accuracy is already an acceptable compromise. The purpose of a DAO action in a semi-automatic is mostly to avoid the change in trigger pull between the first and subsequent shots that one experiences in a DA/SA pistol, while avoiding the perceived danger of carrying a cocked single-action handgun, although it also avoids having to carry a cocked and loaded pistol, or having to lower
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3200-524: Is extracted and ejected as the slide/bolt moves rearwards under recoil , the hammer /striker is cocked by the slide/bolt movement, and a new round from the magazine is pushed into the chamber when the slide/bolt returns forward under spring tension. This sets up the following shot, which is fired as soon as the trigger is pulled again. Most pistols use a short recoil operation to perform this, but some pistols use simple blowback or gas operation mechanisms. Most types of semi-automatic pistols rely on
3300-415: Is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin /striker until the trigger has been released and reset. A semi-automatic pistol recycles part of the energy released by the propellant combustion to move its bolt , which is usually housed inside the slide . After a round of ammunition is fired, the spent cartridge casing
3400-597: Is named for the sudden loss of resistance when the sear reaches the point of release, which is described as resembling the breaking of rigid materials when the strength fails under stress . The actuation force required to overcome the sear resistance during the break is known as the trigger weight , which is usually measured with a force gauge in newtons in SI units , or alternatively kilograms or grams in metric units, and pounds and/or ounces in US customary units . The break
3500-404: Is often considered the most critical stage of the trigger pull for achieving good practical accuracy, since it happens just prior to the shot being discharged and can cause some unwanted shakes from the shooter's hand at the instant of firing. Shooter preferences vary; some prefer a soft break with a smooth but discernible amount of trigger travel during firing, while others prefer a crisp break with
3600-399: Is the difference between the first double-action pull and subsequent single-action pulls. DAO firearms resolve some DA/SA shortcomings by making every shot a double-action shot. Because there is no difference in pull weights, training and practice are simplified. Additionally, the heavier trigger pull can help to prevent a negligent discharge under stress. This is a particular advantage for
3700-399: Is to rack the slide, clearing the round and recocking the hammer. While this can be advantageous in that many rounds will fire on being struck a second time, and it is faster to pull the trigger a second time than to cycle the action, if the round fails to fire on the second strike, the user will be forced to clear the round anyway, thus using up even more time than if they had simply done so in
3800-483: The 7.65 mm Borchardt cartridge, had been designed in 1893 and made its public debut in 1894. Borchardt based the principle of the C-93's mechanism in large part upon Maxim's toggle-lock. The C-93 featured a locking mechanism modeled after the human knee, which is called Kniegelenk in German (knee joint). The C-93 proved mechanically reliable but was too large and bulky to receive widespread acceptance. Equipped with
3900-602: The 7.65 mm Borchardt . The Mauser was one of the first self-loading pistols used extensively in battle, notably the Second Boer War of 1899–1902. These pistols were made in 7.63 mm Mauser , or 9×25mm Mauser, along with some models eventually being made in 9 mm Parabellum and a small number in .45 ACP for China. 1898 saw the Schwarzlose Model 1898 , a semi-automatic pistol invented by Prussian firearm designer Andreas Wilhelm Schwarzlose . It
4000-632: The LeMat , as well as early metallic cartridge revolvers such as the Colt Model 1873 "Single Action Army" (named for its trigger mechanism) and Smith & Wesson Model 3 , all of which required a thumb to cock the hammer before firing. Single-action triggers with manually cocked external hammers lasted a while longer in some break-action shotguns and in dangerous game rifles, where the hunter did not want to rely on an unnecessarily complex or fragile weapon. While single-action revolvers never lost favor in
4100-558: The Smith & Wesson Centennial , the Type 26 Revolver , and the Enfield No. 2 Mk I* and Mk I** revolvers, in which there is no external hammer spur, or which simply lack the internal sear mechanism capable of holding the hammer in the cocked position. A double-action/single-action (DA/SA) trigger is a hybrid design combining the features of both single- and double-action mechanisms. It
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4200-598: The Smith & Wesson Model 27 , S&W Model 60 , the Colt Police Positive , Colt Python , etc. Early double-action revolvers included the Beaumont–Adams and Tranter black-powder muzzleloaders . There are some revolvers that can only be fired in double-action mode (DAO), but that is almost always due to existing double-action/single-action models being modified so that the hammer cannot be cocked manually, rather than from weapons designed that way from
4300-418: The propellant powder within the cartridge case and thus discharges the projectile . The trapping interface between the trigger and the hammer/striker is typically referred to as the sear surface. Variable mechanisms will have this surface directly on the trigger and hammer or have separate sears or other connecting parts. The trigger pull can be divided into three mechanical stages: When considering
4400-472: The "ticklers" on medieval European crossbows . Although the word "trigger" technically implies the entire mechanism (known as the trigger group ), colloquially it is usually used to refer specifically to the trigger blade. Most firearm triggers are "single-action", meaning that the trigger is designed only for the single function of disengaging the sear , which allows for a spring -tensioned hammer / striker to be released. In "double-action" firearm designs,
4500-475: The 20th century has been for semi-automatic pistols to replace revolvers for military use, although the transition has been slower in police and civilian use. As of 2011 , revolvers are mainly used in jurisdictions that permit their use for civilian self-defense, hunting, plinking , and target practice. Semi-automatic pistols are by far the most popular for concealed carry by civilians, primary handguns for police and military use, backup guns for police use, and where
4600-698: The Belgian firm of Fabrique Nationale (FN) and later by Colt in the U.S. Browning's first successful design was the Browning M1900 . Like Georg Luger 's work conducted around the same time in Germany, it was designed alongside a in 7.65 mm cartridge, but the 7.65 mm Browning (aka .32 Auto) differs substantially from Luger's 7.65 mm Parabellum . Browning went on to design .25, .38, .380, and .45 ACP cartridges for his semi-automatic pistol designs. Browning must be given credit for developing
4700-601: The FN Browning Hi-Power , announced in 1922, during the last years of his life, working on this design until his death in 1926. This was a 9 mm semi-automatic pistol capable of holding 13 rounds in the magazine (plus one chambered). The next notable design was the 7.65 mm Luger by Georg Luger , which although successful in its function, nonetheless failed to have adequate stopping power and failed to win widespread acceptance. In 1902, Luger's subsequent and similar P08 in 9 mm Parabellum overcame
4800-542: The SP 2022 variant is still listed on the SIG Sauer website. The SIG Pro was marketed as a lightweight and compact alternative to the "legacy" SIG Sauer handguns in an increasingly competitive and budget-oriented law enforcement market. There have been two generations of SIG Pro offerings, with five total variants. The below are each hammer -fired semi-automatic pistols operating in double action / single action (DA/SA), with
4900-575: The US right up until the birth of the semi-automatic pistol , double-action revolvers such as the Beaumont–Adams were designed in Europe before the American Civil War broke out and saw great popularity all through the latter half of the 19th century, with certain numbers being sold in the US as well. While many European and some American revolvers were designed as double-action models throughout
5000-507: The United States, selective-fire weapons are not legally available to civilians unless they live in a state that allows civilian ownership of National Firearms Act or Title II weapons. Self-loading automatic pistols can be divided into "blowback" and "locked breech" categories according to their principle of operation. The blowback operating principle is suitable for smaller, lower-powered calibers, such as .32 ACP and .380 ACP , as
5100-447: The cocked position when it is pulled to the rear and the trigger is not depressed. In a revolver , this means that simply squeezing the trigger when the hammer is lowered will both cock and release it. If the user uses their thumb to pull the hammer to the back, but does not press the trigger, the mechanism will lock the hammer in the cocked position until the trigger is pressed, just like a single action. Firing in double-action mode allows
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#17328014230865200-616: The factory. A release trigger releases the hammer or striker when the trigger is released by the shooter, rather than when it is pulled. A binary trigger is a trigger for a semiautomatic firearm that drops the hammer both when the trigger is pulled, and also when it is released. Examples include the AR-15 series of rifles, produced by Franklin Armory, Fostech Outdoors, and Liberty Gun Works. The AR-15 trigger as produced by Liberty Gun Works only functions in pull and release mode, and does not have
5300-421: The first place. The Taurus PT 24/7 Pro pistol (not to be confused with the first-generation 24/7 which was a traditional pre-set) offered this feature starting in 2006. The Walther P99 Anti-Stress is another example. A double-crescent trigger provides select fire capability without the need for a fire mode selector switch. Pressing the upper segment of the trigger produced semi-automatic fire, while holding
5400-481: The hammer from accidentally dropping, or a " decocker " – a lever that safely and gently drops the hammer (i.e. decocks the gun ) without fear of the gun firing. The latter is the more popular because, without a decocker, the user is forced to lower the hammer by hand onto a loaded chamber, with all of the attendant safety risks that involves, to return the gun to double-action mode. Revolvers almost never feature safeties, since they are traditionally carried un-cocked, and
5500-430: The hammer is manually lowered again. This gives the positive aspects of a single-action trigger without the need to carry "cocked and locked" (with a loaded chamber and cocked hammer), or with an empty chamber, which requires the user to chamber a round before firing. A potential drawback of a DA/SA weapon is that the shooter must be comfortable dealing with two different trigger pulls: the longer, heavier DA first pull and
5600-656: The hammer on a loaded chamber, if one only fires a partial magazine. A good example of this action in a semi-automatic is the SIG Sauer DAK trigger, or the DAO action of the Sig P250 . For striker-fired pistols such as the Taurus 24/7 , the striker will remain in the rest position through the entire reloading cycle. This term applies most often to semi-automatic handguns; however, the term can also apply to some revolvers such as
5700-420: The hammer or striker may be either thumb-cocked or activated by pulling the trigger when firing the first shot. The hammer or striker is recocked automatically during each firing cycle. In double-action pistols, the first pull of the trigger requires roughly twice as much pressure as subsequent firings, since the first pull of the trigger also cocks the hammer (if not already cocked by hand). The Beretta 92F/FS
5800-684: The hammer requires the user to physically cock it prior to every shot; unlike a DA/SA gun, which cocks itself every time the slide is cycled. There are many examples of DA/SA semi-automatics, the Little Tom Pistol being the first, followed up by the Walther PPK and Walther P38 . Modern examples include weapons such as the Beretta 92 , among others. Almost all revolvers that are not specified as single-action models are capable of firing in both double- and single-action mode, for example,
5900-504: The hammer/striker (and nothing else), while the hammer/striker must be cocked by separate means. Almost all single-shot and repeating long arms (rifles, shotguns , submachine guns , machine guns, etc.) use this type of trigger. The "classic" single-action revolver of the mid-to-late 19th century includes black powder caplock muzzleloaders such as the Colt 1860 "Army" Model , and Colt 1851 "Navy" Model , and European models like
6000-468: The late 1930s and early 1940s, Walther introduced the first "double-action" (actually DA/SA hybrid) semi-automatic pistols, the PPK and P.38 models, which featured a revolver-style double-action trigger, allowing the weapon to be carried with a round chambered and the hammer lowered. After the first shot, they would fire subsequent shots like a single-action pistol. These pistols rapidly gained popularity, and
6100-420: The late 19th century, for the first half of the 20th century, all semi-automatic pistols were single-action weapons, requiring the weapon to be carried cocked and loaded with the safety on, or uncocked with an empty chamber ( Colt M1911 , Mauser C96 , Luger P.08 , Tokarev TT , Browning Hi-Power ). The difference between these weapons and single-action revolvers is that while a single-action revolver requires
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#17328014230866200-445: The lower segment of the trigger produced fully automatic fire. Though considered innovative at the time, the feature was eliminated on most firearms due to its complexity. Examples include MG 34 , Kulsprutegevär m/40 automatic rifle , M1946 Sieg automatic rifle , Osario Selectiva, and Star Model Z62 . A progressive , or staged trigger allows different firing rates based on how far it is depressed. For example, when pulled lightly,
6300-415: The optional ability to cock the hammer separately, reducing the trigger to perform just one action. This is opposed to "double-action only" firearms, which completely lack the capability to fire in single-action mode. In a DA/SA trigger, the mechanism is designed with an internal sear that allows the trigger to both cock and release the hammer/striker when fully pulled, or to merely lock the hammer/striker in
6400-410: The pin's impact; at other times, it operates as a single-action striker-fired firearm. In contrast, a single-action (SA) semi-automatic pistol must be cocked by first operating the slide or bolt, or, if a round is already chambered, by cocking the hammer manually. The M1911 is an example of this style of action. All SA semi-automatic pistols exhibit this feature and automatically cock the hammer when
6500-420: The pistol and is easily accessible only for those who are holding the pistol in the right hand. Many modern SA semi-automatic pistols have had their safety mechanisms redesigned to provide a thumb safety on both sides of the pistol (ambidextrous), thereby better meeting the needs of left-handed, as well as right-handed users. Many SA semi-automatic pistols have a hammer position known as " half-cocked ". Squeezing
6600-466: The practical accuracy of a firearm, the trigger takeup is often considered the least critical stage of the trigger pull. Often triggers are classified as either single-stage or two-stage based on the takeup. A single-stage trigger is often called direct trigger and is popular on hunting rifles. A two-stage trigger is often called pressure trigger and is popular on competition rifles. Some fully adjustable triggers can be adjusted to function as either
6700-502: The primer. Examples of pre-set strikers are the Glock , Smith & Wesson M&P , Springfield Armory XD -S variant (only), Kahr Arms , FN FNS series and Ruger SR series pistols. This type of trigger mechanism is sometimes referred to as a Striker Fired Action or SFA. Examples of pre-set hammers are the Kel-Tec P-32 and Ruger LCP pistols. Pre-set hybrid triggers are similar to a DA/SA trigger in reverse. The first pull of
6800-500: The problem of inadequate stopping power and featured a greatly improved Borchardt-type Kniegelenk ("knee-joint") locking mechanism. Unlike Browning's locked-breech design, the barrel in a Kniegelenk design does not tip up and down while the gun is fired, thereby theoretically improving shooting accuracy. Luger's P.08 was adopted by the German military and served as their standard sidearm in World War I . During World War II, Germany
6900-408: The resistance of the recoil spring and mass of the slide are sufficient to retard the opening of the breech until the projectile has left the barrel and breech pressure has dropped to a safe level. For more powerful calibers such as the 9 mm Parabellum (9 mm) and .45 ACP , some form of locked-breech is needed to retard breech opening, as an unlocked blowback pistol in these calibers requires
7000-461: The same .45 ACP ammunition used in the M1911A1, because of the great demand for handguns and the need to adopt a common cartridge for use in both semi-automatic pistols and revolvers. After World War II, most nations eventually adopted 9 mm Parabellum caliber pistols employing some variant of Browning's locked-breech design for their standard-issue military pistols. The most popular early choice
7100-490: The same principles to handguns, including Maxim. Maxim's designs for smaller firearms using his recoil-powered ideas never went into production. In the 1880s, other designers worked on self-loading designs. The Salvator Dormus was the first semi-automatic pistol followed closely by the Schönberger-Laumann 1892 . The first model to gain any commercial success was Hugo Borchardt 's C-93 , which, together with
7200-401: The set trigger, and then pulling the firing trigger. A double set, double phase trigger can be operated as a standard trigger if the set trigger is not pulled, or as a set trigger by first pulling the set trigger. Double set, double phase triggers offer the versatility of both a standard trigger and a set trigger. Pre-set strikers and hammers apply only to semi-automatic handguns. Upon firing
7300-402: The shell casing and reloads the chamber. This mode of operation generally allows for faster reloading and storing a larger number of cartridges than a revolver. Some modern semi-automatic pistols are exclusively double-action (DA or DAO) trigger function; that is, once a round is chambered, each trigger pull cocks the hammer, striker, or firing pin, and additionally releases the same to fire
7400-433: The shorter, lighter subsequent SA pulls. The difference between these trigger pulls can affect the accuracy of the crucial first few shots in an emergency situation. Although there is little need for a safety on a DA/SA handgun when carrying it loaded with the hammer down, after the first shots are fired, the hammer will be cocked and the chamber loaded. Thus, most DA/SA guns either feature a conventional safety that prevents
7500-406: The shortest, lightest, and smoothest pull available. The pull is also consistent from shot to shot so no adjustments in technique are needed for proper accuracy. On a single-action revolver, for which the hammer must be manually cocked prior to firing, an added level of safety is present. On a semi-automatic, the hammer will be cocked and made ready to fire by the process of chambering a round, and as
7600-430: The slide is first "racked" to chamber a round. A round can also be manually inserted in the chamber with the slide locked back. Then the safety can be applied. It is generally not a good idea to load a round manually as this can cause excessive wear on the extractor as semi-automatic firearms were designed to have cartridges loaded from the bottom via the magazine. The normal mode of carrying an SA semi-automatic pistol
7700-414: The spring under tension , an intermediate mechanism to transmit the kinetic energy from the spring releasing, and a firing pin to eventually strike and ignite the primer. There are two primary types of striking mechanisms – hammer and striker . A hammer is a pivoting metallic component subjected to spring tension so when released will swing forward to strike a firing pin like a mallet hitting
7800-471: The striker is partially cocked back as the slide closes. This allows for significantly shorter trigger pulls than DAO. The trigger spring can be replaced with a lighter one and paired with a low-strength sear connector resulting in lightened trigger pulls to improve a shooter's accuracy (like models G34 and G35 ). Standard modern semi-automatic pistols are usually double-action (DA), also sometimes known as double-action/single-action (DA/SA). In this design,
7900-419: The term "automatic pistol" technically refers to a fully automatic machine pistol , which is capable of continuously firing multiple rounds with a single pull of the trigger, although in popular American usage it is also used as a synonym for any self-loading pistol, the vast majority of which are semi-automatic. In colloquial usage, because machine pistols are very rare on the market, an "automatic pistol",
8000-399: The thumb safety (accessible only to right-handed users) positioned in the off (or ready-to-fire) mode. The primary advantage of the half-cocked position versus the uncocked position in that particular scenario was added sound suppression (of the click of the weapon being cocked). A secondary advantage was the avoidance of accidental discharges if the gun was accidentally dropped. The half-cock
8100-411: The traditional single-action-only pistols rapidly lost favor, although they still retain a dedicated following among enthusiasts. Today, a typical revolver or semi-automatic pistol is a DA/SA one, carried in double-action mode but firing most of its shots in single-action mode. A double-action trigger, also known as double-action only (DAO) to prevent confusion with the more common hybrid DA/SA designs,
8200-421: The trigger also performs the additional function of cocking the hammer – and there are many designs where the trigger is used for a range of other functions. Firearms use triggers to initiate the firing of a cartridge seated within the gun barrel chamber . This is accomplished by actuating a striking device through a combination of mainspring (which stores elastic energy ), a trap mechanism that can hold
8300-414: The trigger break. It can be a very critical factor for accuracy because shaking movements during this phase may precede the projectile leaving the barrel and is especially important with firearms with long barrels, slow projectiles and heavy trigger weights, where the more significant resistance drop can make the trigger finger overshoot and shake in an uncontrolled fashion. Having some overtravel provides
8400-409: The trigger is pre-set. If the striker or hammer fail to discharge the cartridge, the trigger may be pulled again and will operate as a double-action only (DAO) until the cartridge discharges or the malfunction is cleared. This allows the operator to attempt a second time to fire a cartridge after a misfire malfunction, as opposed to a single-action, in which the only thing to do if a round fails to fire
8500-479: The trigger is tasked to perform, a.k.a. the trigger action (not to be confused with the action of the whole firearm , which refers to all the components that help handle the cartridge, including the magazine , bolt , hammer and firing pin / striker , extractor and ejector in addition to the trigger). While a trigger is primarily designed to set off a shot by releasing the hammer/striker, it may also perform additional functions such as cocking (loading against
8600-612: The trigger leads to the release of much more energy. Most triggers use a small flattened lever (called the trigger blade ) depressed by the index finger , but some weapons such as the M2 Browning machine gun or the Iron Horse TOR ("thumb-operated receiver") use a push-button -like thumb-actuated trigger design, and others like the Springfield Armory M6 Scout use a squeeze-bar trigger similar to
8700-431: The trigger pull begins. With semi-automatics, this means that unlike DA/SA weapons, the hammer does not remain cocked after the first round is fired, and every shot is in double-action mode. With revolvers, this means that one does not have the option of cocking the gun before shooting and must always shoot it in double action mode. Although there have been revolvers that were designed with trigger mechanisms totally lacking
8800-540: The trigger will not fire the gun when it is in the half-cocked position, and neither will dropping the gun in this state cause an accidental discharge. During World War II , in the Asiatic-Pacific Theater , an unofficial and unapproved carry mode for the SA M1911 by left-handed U.S. soldiers in combat was carrying the gun with the magazine full, a round chambered, the action in half-cocked position, and
8900-425: The trigger, and it travels to its resting position. On semiauto firearms the movement eventually passes by reset position where trigger-disconnector mechanism resets itself to its resting state, in which pulling the trigger releases the sear. The reset event does not occur in double action firearms and in full auto firearms. There are numerous types of trigger designs, typically categorized according to which functions
9000-514: The trigger, or by pushing forward on a small lever attached to the rear of the trigger. This takes up the trigger slack (or "take-up") in the trigger and allows for a much lighter trigger pull. This is colloquially known as a hair trigger . A double set trigger achieves the same result, but uses two triggers: one sets the trigger and the other fires the weapon. Double set triggers can be further classified into two different phases. A double set, single phase trigger can only be operated by first pulling
9100-547: The type of locked-breech action which is commonly used by the vast majority of modern large caliber semi-automatic pistols. One of Browning's most enduring designs was the Colt M1911 , which was adopted by the U.S. military as its service pistol and is in active use since 1911 within some U.S. special forces and Marine units, albeit in modernized forms (the M45A1 Pistol is a prime example). Browning also co-designed
9200-485: The user to manually cock the hammer before each firing, a single-action semi-automatic pistol only requires manual cocking for the first shot, after which the slide will reciprocate under recoil to automatically recock the hammer for a next shot, and is thus always cocked and ready unless the user manually decocks the hammer, encounters a misfiring cartridge , or pulls the trigger on an empty chamber (for older weapons lacking "last round bolt hold open" feature). In
9300-448: The usual five or six shots of a revolver are deemed inadequate. Trigger (firearms)#Double-action only A trigger is a mechanism that actuates the function of a ranged weapon such as a firearm , airgun , crossbow , or speargun . The word may also be used to describe a switch that initiates the operation of other non-shooting devices such as a trap , a power tool , or a quick release . A small amount of energy applied to
9400-416: The weapon can be carried with the hammer down on a loaded chamber, reducing perceived danger of carrying a single-action semi-automatic. When the user is ready to fire, simply pulling the trigger will cock and release the hammer in double action mode. When the weapon fires, the cycling slide automatically cocks the hammer to the rear, meaning that the rest of the shots fired will be in single-action mode, unless
9500-416: The weapon will fire a single shot. When depressed further, the weapon fires at a fully automatic rate. Examples include FN P90 , Jatimatic , CZ Model 25 , PM-63 , BXP , F1 submachine gun , Vigneron submachine gun , Wimmersperg Spz-kr , and Steyr AUG . Each trigger mechanism has its own merits. Historically, the first type of trigger was the single-action. This is the simplest mechanism and generally
9600-723: Was adopted by the (normally unarmed) British police in 1911 and by the Royal Navy and Royal Marines before the First World War, revolvers were generally preferred by most British military . In the Soviet Union, the TT pistol replaced the Nagant M1895 revolver during the war. In the United States, the M1911A1 was adopted as the standard military sidearm. Both Colt and Smith & Wesson produced revolvers chambered for
9700-816: Was chambered for the 7.65×25mm Mauser, but could also shoot the weaker Borchardt ammunition. The Schwarzlose design was most advanced and far ahead of its time, but not widely adopted with less than 1000 pieces being manufactured. Small lots were sold to members of the Russian Social-Democratic Party who were plotting insurrection but were confiscated at the Russian border and issued to the Imperial Russian Frontier Guards. In Belgium , in 1896, American gun designer John Browning developed self-loading semi-automatic pistols. His models were first manufactured in Europe by
9800-406: Was revised by Colt in the 1970s and subsequently other manufacturers – the hammer will fall from half-cock if the trigger is pulled on most newer 1911 type guns. A self-loading pistol reloads the chamber with a new round automatically each time the weapon is fired, without additional action being required by the user. For a semi-automatic pistol, this is typically accomplished by recoil operation. In
9900-546: Was the FN Browning Hi-Power mentioned above; another popular model was the locked-breech Walther P38 because of its many safety features. Over the course of the postwar 20th century, additional popular semi-automatic pistols were introduced, including the Smith & Wesson Model 59 , Beretta 92 , CZ 75 , Glock , SIG Sauer P226 , Walther P88 , Heckler & Koch USP , Kel-Tec P-11 , and Kel-Tec P-32 , among many other models. The almost universal trend since
10000-573: Was the first nation to adopt a double-action pistol, the Walther P38 , which could be carried loaded (with a cartridge chambered) and ready to fire without the risk of an accidental discharge if dropped. The P38 also used Luger's 9 mm Parabellum cartridge. Revolvers were still issued by various major powers, but their use was decreasing. Though the British firm Webley & Scott had developed several adequate self-loading pistols, one of which
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