Glock

This article is about the semi-automatic pistol. For other uses, see Glock (disambiguation).

Glock
A first-generation Glock 17 adopted by the Norwegian Armed Forces under the P80 designation
Type	Semi-automatic pistol Machine pistol (Glock 18)
Place of origin	Austria
Service history
In service	1982–present
Used by	See Users
Production history
Designer	Gaston Glock
Designed	1979–1982
Manufacturer	Glock GmbH
Produced	1982–present
No. built	20,000,000 as of 2020
Variants	See Variants
Specifications
Cartridge	9×19mm Parabellum 10mm Auto .22 LR .357 SIG .380 ACP .40 S&W .45 ACP .45 GAP
Action	Short recoil, locked breech, tilting barrel (straight blowback for Glock 25, 28, and 44)
Feed system	6-, 10-, 13-, 15-, 17-, 19-, 24-, 25-, 31-, 33-, or 40-round detachable box magazine, or 50- or 100-round detachable drum magazine
Sights	Iron sights

Glock (German: [ˈglɔk]; stylized as GLOCK) is a brand of polymer-framed, short-recoil-operated, locked-breech semi-automatic pistols (as well as some rifles and one machine pistol) designed and produced by Austrian manufacturer Glock GmbH. The firearm, designed by company founder Gaston Glock (1929–2023), entered Austrian military and police service in 1982 as the P80 (later known commercially as the Glock 17) after outperforming established competitors in reliability and safety tests. Despite initial market resistance due to its "plastic" construction, the Glock became the first commercially successful line of pistols with a polymer frame.

The weapon uses the company's proprietary "Safe Action" system, which consists of three independent internal safety mechanisms: the trigger safety, the firing pin safety, and the drop safety. These mechanisms prevent accidental discharge without an external on-off switch. The pistols are also noted for their high magazine capacity relative to their weight and their resistance to corrosion, originally achieved through a ferritic nitrocarburizing surface treatment known as Tenifer.

Glock pistols have become the company's most profitable line of products. They are supplied to national armed forces, security agencies, and police forces in at least 48 countries, including the Federal Bureau of Investigation (FBI) and the majority of police agencies in the United States. The product line has evolved through six generations of design changes ("Gen 1" through "Gen 6"). It is available in a wide variety of calibers, including 9×19mm Parabellum, .40 S&W, 10mm Auto, and .45 ACP, as well as various sizes ranging from the full-sized Glock 17 to the subcompact Glock 26 and "slimline" Glock 43.

The widespread adoption of the design has made the Glock rise in popularity and a subject of gun control debates. In the 2020s, the pistols faced scrutiny regarding the proliferation of "Glock switches," illegal aftermarket auto sears that convert the firearms into machine pistols. This led to lawsuits filed by the states of Minnesota and New Jersey in 2024, and legislation in California in 2025 (Assembly Bill 1127), aimed at forcing design changes to prevent such conversions. In October 2025, Glock announced a major "right-sizing" initiative, ceasing production of over thirty variants to streamline manufacturing and introduce redesigned components to mitigate full-auto conversion.

History

The company's founder and head engineer, Gaston Glock (1929–2023), had no experience in firearms design or manufacture when his first pistol, the Glock 17, was being prototyped. Glock had extensive experience in advanced synthetic polymers, which was instrumental in the company's design of the first commercially successful line of pistols with a polymer frame. Glock introduced ferritic nitrocarburizing into the firearms industry as an anticorrosion surface treatment for metal gun parts.

Development

In 1980, the Austrian Armed Forces announced that it would seek tenders for a new, modern duty pistol to replace their World War II–era Walther P38 handguns. The Federal Ministry of Defence of Austria formulated a list of 17 criteria for the new generation service pistol, including requirements that it would be self loading; fire the NATO-standard 9×19mm Parabellum round; the magazines would not require any means of assistance for loading; not be subject to accidental discharge from shock, strike, and drop from a height of 2 m (6 ft 7 in) onto a steel plate. After firing 15,000 rounds of standard ammunition, the pistol was to be inspected for wear. The pistol was to be then used to fire an overpressure test cartridge generating 5,000 bar (500 MPa; 73,000 psi). The normal maximum operating pressure (P_max) for the 9 mm NATO is 2,520 bar (252 MPa; 36,500 psi).

Glock became aware of the Austrian Army's planned procurement, and in 1982, assembled a team of Europe's leading handgun experts from military, police, and civilian sport-shooting circles to define the most desirable characteristics in a combat pistol. Within three months, Glock had developed a working prototype that combined proven mechanisms and traits from previous pistol designs. In addition, the plan was to make extensive use of synthetic materials and modern manufacturing technologies, which led to the Glock 17 becoming a cost-effective candidate.

Several samples of the Glock 17 (so named corresponding to its magazine capacity or because it was the 17th patent procured by the company) were submitted for assessment trials in early 1982. After passing all of the exhaustive endurance and abuse tests, the Glock emerged as the winner. According to Friedrich Dechant, former head of the Austrian Armaments and Defence Technology Agency, the Glock P80 was clearly superior to other handguns in terms of performance, handling, charging capacity and price.

The handgun was adopted into service with the Austrian military and law enforcement in 1982 as the Pistole 80 (P80), with an initial order for 25,000 guns. The Glock 17 outperformed eight different pistols from five other established manufacturers (Heckler & Koch of Germany offered their P7M8, P7M13, and P9S, SIG Sauer of Switzerland bid with their P220 and P226 models, Beretta of Italy submitted their model 92SB-F, FN Herstal of Belgium proposed an updated variant of the Browning Hi-Power, and the Austrian Steyr Mannlicher entered the competition with the GB).

The results of the Austrian trials sparked a wave of interest in Western Europe and overseas, particularly in the United States, where a similar effort to select a service-wide replacement for the M1911 had been going on since the late 1970s (known as the Joint Service Small Arms Program). In late 1983, the United States Department of Defense inquired about the Glock pistol and received four samples of the Glock 17 for unofficial evaluation. Glock was then invited to participate in the XM9 Personal Defense Pistol Trials, but declined because the DOD specifications would require extensive retooling of production equipment and providing 35 test samples in an unrealistic time frame.

In 1985, after joint Norwegian and Swedish trials from 1983 to 1985, the Glock 17 was accepted into service as the P80 in Norway and, in 1988, as the Pistol 88 in Sweden, where it surpassed all prior NATO durability standards. As a result, the Glock 17 became a standard NATO-classified sidearm and was granted a NATO Stock Number (1005-25-133-6775). By 1992, some 350,000 pistols had been sold in more than 45 countries, including 250,000 in the United States alone.

Starting in 2013, the British Armed Forces began replacing the Browning Hi-Power pistol with the Glock 17 Gen 4, due to concerns about weight and the external safety of the Hi-Power. The British preferred the Glock 17 Gen 4 over the Beretta Px4 Storm, FN FNP, Heckler & Koch P30, SIG Sauer P226, Smith & Wesson M&P, and Steyr M9A1 of which 19 pistols each, all chambered in 9×19 mm Parabellum, were entered in the R9GSP trials.

The French Armed Forces (FAF) in 2020 began replacing their MAC Mle 1950 and, to a lesser extent, their PAMAS G1 pistols with Glock 17 Gen 5 models specifically made for the FAF. The French preferred the Glock 17 Gen 5 over the HS2000 and CZ P-10 offerings that also made it to the final selection phase.

Product evolution

Glock has updated its basic design several times throughout its production history.

First-generation models

A "first-generation" Glock 17 with the slide locked back, displaying its vertical barrel tilt

The first-generation (Gen 1) Glock pistols are most notably recognized by their smoother "pebble finish" grip and frame with no finger grooves. The Gen 1 frame pattern and design was used by Glock from 1982 through 1988 and pre-dates the checkered grip patterns used in the second generation of Glock pistols. The first Glock 17s imported to the US were serialized with an alphanumeric (two-letter prefix followed by three numbers) stamped into the slide, barrel, and a small metal plate inserted into the bottom side of the polymer frame. The first documented Glock 17s (by serial number) imported into the US were from the AF000 series in January 1986, followed by AH000, AK000, and AL000. These early Glock (Gen 1) pistols (serial number prefix AF through AM) were also manufactured with a barrel that had a smaller overall diameter and thinner bore walls, later known as "pencil barrels". The barrels were later redesigned with thicker bore walls, and manufacturing continued to evolve, improving the design of Glock pistols.

Many of the first-generation Glocks were shipped and sold in the iconic "Tupperware" style plastic boxes. The earliest Glock boxes had ammunition storage compartments that allowed for 17 rounds of 9mm to be stored with the pistol. Glock later changed this box design to meet BATF import requirements, and removed the ammunition storage compartments.

Second-generation models

A "second-generation" Glock 17, identified by the checkering on the front and rear straps of the pistol grip and trigger guard

A mid-life upgrade to the Glock pistols involved adding checkering to the front strap and trigger guard, and adding checkering and serrations to the back strap. These versions, introduced in 1988, were informally referred to as "second-generation" or Gen2 models. However, Glock did not mark the pistols Gen2. In 1991, an integrated recoil spring assembly replaced the original two-piece recoil spring and tube design. The magazine was slightly modified, changing the floorplate and fitting the follower spring with a resistance insert at its base.

Third-generation models

A "third-generation" Glock 17C, identified by the addition of an extra cross pin above the trigger, finger grooves, a reshaped extractor that serves as a loaded chamber indicator, and an accessory rail

In 1998, the frame was further modified with an accessory rail (called the "Universal Glock rail") similar to a Picatinny rail to allow the mounting of laser sights, tactical lights, and other accessories. Thumb rests on both sides of the frame, and finger grooves were added to the front strap. Glock pistols with these upgrades are informally referred to as (early) "third-generation" models. Later third-generation models additionally featured a modified extractor that serves as a loaded chamber indicator, and the locking block was enlarged, along with the addition of an extra cross pin to aid the distribution of bolt thrust forces exerted by the locking block. This cross pin is known as the locking block pin and is located above the trigger pin.

The polymer frames of third-generation models can be black, flat dark earth, or olive drab. Besides that, non-firing dummy pistols ("P" models) and non-firing dummy pistols with resetting triggers ("R" models) have a bright red frame, and Simunition-adapted practice pistols ("T" models) a bright blue frame for easy identification.

In 2009, the Glock 22 RTF2 (Rough Textured Frame 2) (chambered in .40 S&W) was introduced. This pistol featured new checkering on the grip and new scalloped (fish-gill-shaped) serrations on the sides of the slide. Many of the existing models became available in the RTF2 version, including the 17, 31, 32, 23, 21, and 19. Some of those did not have the fish gills.

Fourth-generation models

A "fourth-generation" Glock 17, identified by an enlarged and reversible magazine release catch, modified rough texture frame grip checkering, interchangeable backstraps, and a "Gen4" rollmark on the slide

A "fourth-generation" Glock 19

At the 2010 SHOT Show, Glock presented the "fourth generation", now dubbed "Gen4" by Glock itself. Updates centered on ergonomics and the recoil spring assembly. The initial two fourth-generation models announced were the full-sized Glock 17 and Glock 22, chambered for the 9×19mm Parabellum and .40 S&W cartridges, respectively. The pistols were displayed with a modified rough-textured frame (RTF-4), front grip strap with finger grooves, interchangeable backstraps of different sizes, and an accessory rail. "Gen4" is rollmarked on the slide next to the model number to identify the fourth-generation pistols.

The basic grip size of the fourth-generation Glock pistols is slightly smaller than that of the previous design. A punch is provided to remove the standard trigger housing pin and replace it with the longer cross pin needed to mount the medium or large backstrap that will increase the trigger distance by 2 mm (0.079 in) or 4 mm (0.16 in). With the medium backstrap installed, the grip size is identical to that of the third-generation pistols. The magazine release catches are enlarged and reversible for left-handed use. To use the exchangeable magazine release feature, fourth-generation Glock magazines have a notch cut on both sides of the magazine body. Earlier versions of the magazines will not lock into Gen4 pistols if the magazine release button has been moved to be operated by a left-handed user. Gen4 magazines will work in older models.

Mechanically, fourth-generation Glock pistols are fitted with a dual-recoil-spring assembly to reduce perceived recoil and extend service life. Earlier subcompact Glock models, such as the Glock 26 and Glock 30, already used a dual recoil spring assembly, which was carried over to the fourth-generation versions of those models. The slide and barrel shelf have been resized, and the front portion of the polymer frame has been widened and internally enlarged to accommodate the dual recoil spring assembly. The trigger mechanism housing has also been modified to fit into the smaller-sized grip space.

The introduction of fourth-generation Glock pistols continued in July 2010 when the Glock 19 and Glock 23, the reduced size "compact" versions of the Glock 17 and Glock 22, became available for retail. In late 2010, Glock continued the introduction of fourth-generation models with the Glock 26 and Glock 27 "subcompact" variants.

In January 2013, more fourth-generation Glock pistols were introduced commercially during the annual SHOT Show, including the Glock 20 Generation 4 along with other fourth-generation Glock models.

2011 recoil spring assembly exchange program

In September 2011, Glock announced a recoil spring exchange program in which the manufacturer voluntarily offered to exchange the recoil spring assemblies of its fourth-generation pistols (except the "subcompact" Glock 26 and Glock 27 models) sold before 22 July 2011 at no cost "to ensure our products perform up to GLOCK's stringent standards", according to the company.

M series

On 29 June 2016, the United States Federal Bureau of Investigation (FBI) awarded a contract to Glock to provide new 9×19mm Parabellum chambered duty pistols. The solicitation specifications deviated from the specifications of Glock's fourth-generation models. Features found in the M series pistols evolved into what would become Glock's Fifth Generation or Gen5 pistols.

In August 2016, the Indianapolis Metro Police Department (IMPD) started training with a batch of Glock 17M pistols. The most obvious difference with the Glock fourth- and fifth-generation models on published images is the omission of finger grooves on the grip. In October of that year, the IMPD issued a 17M voluntary recall following failures encountered while dry firing the pistols during training. According to Major Riddle with the IMPD, "Glock is working to correct the problem and we hope to begin issuing the new [17Ms] as soon as December."

Fifth-generation models

A "fifth generation" Glock 17 Gen 5

In August 2017, Glock presented the "fifth generation" or "Gen 5", carrying forward much of the feature set developed for the FBI-contract M-series pistols. The revisions centered on ergonomics and improving reliability. Many parts of fifth-generation Glock pistols cannot be interchanged with those of the previous generations. The two fifth-generation models announced were the Glock 17 and Glock 19, chambered for the 9×19mm Parabellum. Some conspicuous changes on the fifth-generation models are ambidextrous slide stop levers, DLC surface finish for barrel and slide, a barrel featuring a revised style of polygonal rifling (called the "Glock Marksman Barrel" by Glock), a deeper recessed barrel crown, omission of the finger grooves on the grip, a flared magazine well, and a reintroduction of a half-moon-shaped cutout on the bottom front of the grip intended to aid forcible extraction of a stuck magazine from the flared magwell. The locking block pin, located above the trigger pin that was introduced in the third generation, is omitted. Many internal parts were revised less conspicuously.

The Gen 5 progressed through several sub-iterations over its production run. The earliest examples (2017–2019) shipped without front slide serrations and featured a dust cover profile that did not match the beveled slide nose. A running change added the matching frame bevel, and in mid-2019 Glock introduced the "FS" (front serrations) variant, which added serrations to the forward slide and dropped the half-moon magazine cutout, along with an updated breech face. "Gen 5" is rollmarked on the slide next to the model number to identify the fifth-generation pistols. The magazines were also revised for the fifth-generation models: the redesigned magazine floor plates feature a forward protruding lip to offer grip for manual assisted extraction, and the magazine follower became orange colored for easier visual identification.

Discontinuation of prior generations and launch of V-series models

In October 2025, Glock announced that it would cease production of more than 30 variants of its handguns, with shipments of most Generation 3, 4, and 5 double-stack and crossover models ending November 30, 2025. The decision was cited by Glock as a streamlining and "right-sizing" measure, but was also prompted by passage of legislation in the United States against pistols that can be easily converted to fully automatic fire (through the use of a Glock switch or other means). The single-stack slimline models (Glock 42, 43, 43X, and 48) were unaffected and continue in production.

In December 2025, Glock launched the "V Series" as replacements for the discontinued models, marked with a "V" designation on the slide and frame (e.g., G17 V, G19 V, G45 V, G26 V, G20 V MOS, G23 V, G21 V MOS, G44 V). V Series pistols feature redesigned trigger bars, revised slide rails, a narrowed firing pin channel, and modified rear plates designed to hinder the installation of full-auto conversion devices. Following the introduction of the sixth-generation pistols in January 2026, the V Series continues in production as Glock's lower-cost baseline offering and remains the only avenue for models not offered in Gen6 configuration, including the Glock 20, 23, 26, and 44.

Sixth-generation models

On December 6, 2025, Glock announced the "sixth generation" or "Gen6" of its pistol line, with commercial availability starting January 20, 2026, coinciding with the pistols' public debut at SHOT Show 2026 in Las Vegas. The initial U.S. lineup consists of three models chambered in 9×19mm Parabellum: the Glock 17 Gen6, Glock 19 Gen6, and Glock 45 Gen6, with the Glock 49 Gen6 offered internationally. Revisions center on ergonomics, trigger design, and an integrated optic-ready system. Notable exterior changes include a reshaped grip with a more pronounced palm swell, an extended thumb rest, an enlarged beavertail, an aggressively undercut trigger guard, deeper angled slide serrations, and a new flat-faced trigger. The frames feature a new "RTF6" grip texture that combines two textures across an expanded surface area including the thumb rest. All standard-frame Gen6 pistols include the new Gen6 optic-ready system, which replaces the MOS mounting system with a deeper slide cut allowing optics to sit lower, and uses a polymer plate that acts as a crush washer to absorb shear force during recoil. Gen6 pistols incorporate the internal switch-resistance modifications introduced in the V-series (revised slide rails, narrowed firing pin channel, and modified trigger bar geometry) along with additional refinements. Contrary to pre-release speculation, the Gen6 does not incorporate a modular Fire Control Unit (FCU), continuing Glock's philosophy of evolutionary rather than revolutionary design. Each pistol ships with three magazines, a cleaning kit, speed loader, backstrap set, three optic plates, and a hard storage case. Gen6 pistols retain compatibility with existing Glock magazines and are priced at the same MSRP as Gen5 models.

Design details

Operating mechanism

The Glock 17 is a short recoil–operated, locked-breech semi-automatic pistol that uses a modified Browning cam-lock system adapted from the Hi-Power pistol. The firearm's locking mechanism uses a linkless, vertically tilting barrel with a rectangular breech that locks into the ejection port cut-out in the slide (the SIG Sauer system). During the recoil stroke, the barrel initially moves rearward, locked together with the slide about 3 mm (0.12 in), until the bullet leaves the barrel and the chamber pressure drops to a safe level. A ramped lug extension at the base of the barrel then interacts with a tapered locking block integrated into the frame, forcing the barrel down and unlocking it from the slide. This camming action terminates the barrel's movement while the slide continues back under recoil, extracting and ejecting the spent cartridge casing. The slide's uninterrupted rearward movement and counter-recoil cycle are characteristic of the Browning system.

Glock pistols incorporate several features intended to enhance reliability under adverse conditions, such as advanced metal coatings, "stub" slide guides instead of true frame rails, and an unusual cocking mechanism in which the trigger is partially responsible for cocking the striker. By relying partially on force from the shooter's trigger finger to cock the striker, a Glock effectively reduces the load on the recoil spring as the slide moves forward into battery. In contrast, almost all other striker-fired pistols on the market rely fully on the recoil spring to cock the striker.

Features

A subcompact Glock 30 field stripped to its main groups with a .45 ACP round

The slide features a spring-loaded claw extractor, and the stamped sheet metal ejector is pinned to the trigger mechanism housing. Pistols after 2002 have a reshaped extractor that serves as a loaded chamber indicator. When a cartridge is present in the chamber, a tactile metal edge protrudes slightly out immediately behind the ejection port on the right side of the slide. The striker firing mechanism has a spring-loaded firing pin that is cocked in two stages that the firing pin spring powers. The factory-standard firing pin spring is rated at 24 N (5.4 lb_f), but by using a modified firing pin spring, it can be increased to 28 N (6.3 lb_f) or to 31 N (7.0 lb_f). When the pistol is charged, the firing pin is in the half-cock position. As the trigger is pulled, the firing pin is then fully cocked. At the end of its travel, the trigger bar is tilted downward by the connector, releasing the firing pin to fire the cartridge. The connector resets the trigger bar so that the firing pin will be captured in half-cock at the end of the firing cycle. This is known as a preset trigger mechanism, referred to by the manufacturer as the "Safe action" trigger. The connector ensures that the pistol can fire only semiautomatically.

The factory-standard, two-stage trigger has a trigger travel of 12.5 mm (0.49 in) and is rated at 25 N (5.6 lb_f), but by using a modified connector, it can be increased to 35 N (7.9 lb_f) or lowered to 20 N (4.5 lb_f). In response to requests from American law enforcement agencies for a two-stage trigger with increased trigger pull, Glock introduced the NY1 (New York) trigger module, which features a flat spring in a plastic housing that replaces the trigger bar's standard coil spring. This trigger modification is available in two versions: NY1 and NY2 that are rated at 25 N (5.6 lb_f) to 40 N (9.0 lb_f) and 32 N (7.2 lb_f) to 50 N (11.2 lb_f), respectively, which require about 20 N (4.5 lb_f) to 30 N (6.7 lb_f) of force to disengage the safeties and another 10 N (2.2 lb_f) to 20 N (4.5 lb_f) in the second stage to fire a shot.

The Glock's frame, magazine body, and several other components are made from a high-strength nylon-based polymer invented by Gaston Glock, called Polymer 2. This plastic was specially formulated to provide increased durability and is more resilient than carbon steel and most steel alloys. Polymer 2 is resistant to shock, caustic liquids, and temperature extremes where traditional steel/alloy frames would warp and become brittle. The injection-molded frame contains four hardened steel guide rails for the slide: two at the rear of the frame, and the remaining pair above and in front of the trigger guard. The trigger guard itself is squared off at the front and checkered. The grip has an angle of 109° and a nonslip, stippled surface on the sides and both the front and rear straps. The frame houses the locking block, which is an investment casting that engages a 45° camming surface on the barrel's lower camming lug. It is retained in the frame by a steel axis pin that holds the trigger and slide catch. The trigger housing is held to the frame by means of a polymer pin. A spring-loaded sheet-metal pressing serves as the slide catch, secured against unintentional manipulation by a raised guard molded into the frame. Because of its polymer construction, there were initially fears that Glock pistols would be invisible to airport X-ray machines, making them easy to illegally import into the United States. In actuality, the majority of the gun's weight comes from steel components, and Polymer 2 is visible to X-ray machines. Concern over the myth led to the passage of the Undetectable Firearms Act in the United States in 1988, banning the manufacture or import of any gun that could pass undetected through a metal detector. The myth was later popularized further by a scene in Die Hard 2 (1990), in which a fictional "Glock 7" is described as a porcelain pistol invisible to airport security.

The Glock pistol has a relatively low slide profile, which holds the barrel axis close to the shooter's hand, making the pistol more comfortable to fire by reducing muzzle rise and allowing faster aim recovery in rapid-fire sequences. The rectangular slide is milled from a single block of ordnance-grade steel using CNC machinery. The barrel and slide undergo two hardening processes before treatment with a proprietary nitriding process called Tenifer. The Tenifer treatment is applied in a 500 °C (932 °F) nitrate bath. The Tenifer finish is between 0.04 and 0.05 mm (0.0016 and 0.0020 in) in thickness, and is characterized by extreme resistance to wear and corrosion; it penetrates the metal, and treated parts have similar properties even below the surface to a certain depth.

The Tenifer process produces a matte gray-colored, nonglare surface with a 64 Rockwell C hardness rating and a 99% resistance to salt water corrosion (which meets or exceeds stainless steel specifications), making the Glock particularly suitable for individuals carrying the pistol concealed as the highly chloride-resistant finish allows the pistol to endure the effects of perspiration better. Glock steel parts using the Tenifer treatment are more corrosion resistant than analogous gun parts having other finishes or treatments, including Teflon, bluing, hard chrome plating, or phosphates. During 2010, Glock switched from the salt bath nitriding Tenifer process to a not exactly disclosed gas nitriding process. After applying the nitriding process, a black Parkerized decorative surface finish is applied. The underlying nitriding treatment will remain, protecting these parts even if the decorative surface finish were to wear off.

A fourth-generation Glock 17 consists of 34 parts. For maintenance, the pistol disassembles into five main groups: the barrel, slide, frame, magazine, and recoil-spring assembly. The firearm is designed for the NATO-standard 9×19mm Parabellum cartridge, but can use high-power (increased pressure) +P ammunition with either full-metal-jacket or jacketed hollow-point projectiles.

Barrel

The hammer-forged barrel has a female type polygonal rifling with a right-hand twist. The stabilization of the round is not by conventional rifling, using lands and grooves, but rather through a polygonal profile consisting of a series of six or eight interconnected noncircular segments (only the .45 ACP and .45 GAP have octagonal polygonal rifling). Each depressed segment within the interior of the barrel is the equivalent of a groove in a conventional barrel. Thus, the interior of the barrel consists of smooth arcs of steel rather than sharply defined slots. Instead of using a traditional broaching machine to cut the rifling into the bore, the hammer forging process involves beating a slowly rotating mandrel through the bore to obtain the hexagonal or octagonal shape. As a result, the barrel's thickness in the area of each groove is not compromised as with conventional square-cut barrels. This has the advantage of providing a better gas seal behind the projectile as the bore has a slightly smaller diameter, which translates into more efficient use of the combustion gases trapped behind the bullet, slightly greater (consistency in) muzzle velocities, and increased accuracy and ease of maintenance.

The newer lines of Glock pistols—i.e., Gen5, G42/43—are equipped with the Glock Marksmanship Barrel, or GMB. While older barrels were somewhat difficult to identify a bullet as coming from a particular barrel with high enough reliability for evidentiary use, the newer GMB ones are designed differently. A study by Stephen Christen and Hans Rudolf Jordi, published in Forensic Science International in February 2019, shows that the new GMB barrels leave more distinctive markings on the fired projectile. These marks were more easily identified than previous pistol barrel markings and were sufficient for reliably tying a bullet to a particular barrel. The study used a comparison microscope and an ABIS (Evofinder).

Safety

Glock pistols lack a traditional on-off safety lever, which Glock markets as an advantage, especially to police departments, as the user can fire immediately without separately manipulating a safety. Instead, the pistols are designed with three independent safety mechanisms to prevent accidental discharge. The system, designated "Safe Action" by Glock, consists of an external integrated trigger safety and two automatic internal safeties: a firing pin safety and a drop safety. The external safety is a small inner lever contained in the trigger. Pressing the lever activates the trigger bar and sheet metal connector. The firing pin safety is a solid, hardened steel pin that, in the secured state, blocks the firing pin channel (disabling the firing pin in its longitudinal axis). It is pushed upward to release the firing pin, firing only when the trigger is actuated and the safety is pushed up by the backward movement of the trigger bar. The drop safety guides the trigger bar in a ramp that is released only when direct rearward pressure is applied to the trigger. The three safety mechanisms are automatically disengaged one after the other when the trigger is squeezed, and are automatically reactivated when the trigger is released.

In 2003, Glock announced the Internal Locking System (ILS) safety feature named Glock Safety Lock. The ILS is a manually activated lock located in the back of the pistol's grip. It is cylindrical in design and, according to Glock, each key is unique. When activated, the lock causes a tab to protrude from the rear of the grip, providing both a visual and tactile indication of whether the lock is engaged. When activated, the ILS renders the Glock unfireable, as well as making it impossible to disassemble. When disengaged, the ILS adds no further safety mechanisms to the Glock pistol. The ILS is available as an option on most Glock pistols. Glock pistols cannot be retrofitted to accommodate the ILS. The lock must be factory-built in Austria and shipped as a special order.

Magazine

A Glock 9×19mm Parabellum 17-round magazine. The numbered witness holes at the back portion visually indicate how many cartridges are contained in the magazine.

The Glock 17 feeds from staggered-column or double-stack magazines that have a 17-round capacity (which can be extended to 19 with an optional floor plate) or optional 24 or 33-round capacity magazines. For jurisdictions that restrict magazine capacity to 10 rounds, Glock offers single-stack, 10-round magazines. The magazines are made of steel and are overmolded with plastic. A steel spring drives a plastic follower. After the last cartridge has been fired, the slide remains open on the slide stop. The slide stop release lever is located on the left side of the frame directly beneath the slide and can be manipulated by the thumb of the right-handed shooter.

Glock magazines are interchangeable between models of the same caliber, meaning that a compact or subcompact pistol will accept magazines designed for the larger pistols chambered for the same round. However, magazines designed for compact and subcompact models will not function in larger pistols because they are not tall enough to reach the slide and magazine release. For example, the subcompact Glock 26 will accept magazines from both the full-size Glock 17 and the compact Glock 19, but the Glock 17 will not accept magazines from the smaller Glock 19 or the Glock 26. The magazines for the Glock 36, the Glock 42, the Glock 43, and the Glock 44 are all unique; they cannot use magazines intended for another model, nor can their magazines be used in other models.

Sights

Standard sighting arrangement of a "first-generation" Glock 17

The first Glock pistols sent to the United States in 1985 failed to meet the BATF import "points" requirement, requiring Glock to quickly develop an adjustable rear sight which allowed for the pistols to be imported and sold commercially in 1986. It is believed that Glock designed and created this adjustable rear sight over a weekend to meet the ATF's importation requirements, and so it was dubbed the "weekend" sight. These first-generation adjustable rear sights extended past the slide and were susceptible to breaking. Even on later models, the front sight can easily become misshapen from friction against the holster, leading to replacements with metal sights, or tritium illuminated night sights.

More commonly today, the Glock 17 has a fixed polymer combat-type sighting arrangement that consists of a ramped front sight and a notched rear sight with white contrast elements painted on for increased acquisition speed – a white dot on the front post and a rectangular border on the rear notch. Some newer rear sights can be adjusted for windage (on certain models, due to the windage sights not being included as a factory default), as they have a degree of lateral movement in the dovetail they are mounted in. Three other factory rear sight configurations are available in addition to the standard 6.5 mm (0.26 in) height sight: a lower impact 6.1 mm (0.24 in) sight, and two higher impact versions – 6.9 mm (0.27 in) and 7.3 mm (0.29 in).

Accessories

The Glock pistol accessories available from the factory include several devices for tactical illumination, such as a series of front rail-mounted "Glock tactical lights" featuring a white tactical light and an optional visible laser sight. An alternative version of the tactical light, using an invisible infrared light and a laser sight, is available and designed to be used with an infrared night vision device. Another lighting accessory is an adapter that mounts a flashlight to the bottom of a magazine.

Polymer holsters in various configurations and matching magazine pouches are available. In addition, Glock produces optional triggers, recoil springs, slide stops, magazine release levers, and maritime spring cups. Maritime spring cups are designed to allow the pistol to be fired immediately after being submerged in water. They feature additional openings that allow liquids to flow and escape around them, offering enhanced reliability when water has penetrated the firing pin assembly channel.

Magazine floor plates (or +2 baseplates), which expand the capacity of the standard magazines by two rounds, are available for models chambered for the 9×19mm Parabellum, .45 GAP, .40 S&W, .357 SIG, and .380 ACP cartridges. In addition to the standard nonadjustable polymer sight line, Glock offers three alternative sight lines. These consist of steel, adjustable, and self-illuminating tritium night rear sights and factory steel and self-illuminating tritium contrast pointer steel front sights.

The Glock 17 along with many variants can accept pistol conversion kits, with one such example being the FAB-Defense KPOS Scout. They can also accept special stocks like the Flux Defense Brace.

Glock switch

Main article: Glock switch

A Glock switch is an aftermarket accessory that depresses the firearm's sear, allowing fully automatic fire. Without the proper license, they are illegal in the United States.

Commemorative, anniversary, engraved, and other rare Glocks

Glock began producing limited edition and commemorative Glocks in 1991. Glock later produced a series of anniversary models to celebrate business milestones and in honor of 20, 25, and 30 years of US sales. Additionally, many law enforcement agencies had the department name, logo, or badges engraved on the slides of issued duty weapons.

Variants

Following the introduction of the Glock 17, numerous variants and versions have been offered. Different model numbers identify variants that differ in caliber, frame, and slide length, except for a few models with a letter suffix (the Glock 17L, 19X, 30S, and 43X).

The original double-stack "small frame" Glock pistols are made in five form factors, all modeled after the original full-sized Glock 17. "Standard" models are designed as full-sized duty firearms with a large magazine capacity. "Compact" models are slightly smaller with reduced magazine capacity and lighter weight while maintaining a usable grip length. "Subcompact" models are designed for easier carry and being lighter and shorter, are intended to be used with two fingers on the grip below the trigger guard, and lack an accessory rail like the larger, after generation two, Glock models. The other two form factors use the full-size "standard" frame with longer slides that include a lower section to fill in the space between the frame's dust cover and the front of the slide. The first of these is the "long slide" models, which were too long for certain IPSC classes, necessitating the creation of the intermediate "competition" models. Currently, the available chamberings for all five form factors are 9mm Parabellum (9×21mm in certain countries) and .40 Smith & Wesson. Additionally, .357 SIG and .45 GAP chamberings are offered in "standard", "compact", and "subcompact" models, while .380 ACP is offered only in "compact" and "sub-compact" models. Recently, so-called "crossover" versions in 9mm Parabellum pair short (front-to-back) "compact" frames with longer "standard" grip lengths. This was initially intended to provide a longer-grip, higher-capacity version of the Glock 19 (Glock 19X and Glock 45). Still, Glock developed the Glock 47 for US Customs and Border Protection, which used the G45 frame with a G17-length slide that included a front section to fill the gap between the dust cover and the front of the slide, a design that maintains the same overall dimensions as the Glock 17. Naturally, the next step was to couple this slide with the Glock 19 Frame, creating the Glock 49.

There are also the wider double-stack "large frame" Glock pistols for use with larger calibers, currently in 10mm Auto and .45 ACP. These models have bigger, wider slides and frames and are larger than the smaller-chambered pistols. These come in only "standard", "subcompact", "competition" (.45 ACP only), and "long slide" (10mm only). Additionally, Glock introduced the "subcompact" Glock 30S in .45 ACP, fitted with the Glock 36's slimmer, lighter slide. Also, in 2007, Glock introduced a "short frame" version of these large frame weapons to provide a grip better suited to small hands. The short frame was originally designed to compete in the now-canceled U.S. military Joint Combat Pistol trials for a new .45 ACP pistol to replace the M9 pistol. Glock's entry featured an optional ambidextrous magazine release and a MIL-STD-1913 rail, along with a reduced backstrap. The Glock 21SF was originally available in three versions: one with a Picatinny rail and an ambidextrous magazine release, and two with a Universal Glock rail, available with or without the ambidextrous magazine release. However, the ambidextrous release and Picatinny rail were soon dropped. As of January 2009, the Glock 20, 21, 29, and 30 were offered in short-framed variations. These models incorporate a 2.5 mm (0.098 in) reduction in trigger reach, and full-sized models feature a 4 mm (0.16 in) reduction in heel depth, which corresponds to an overall reduction in length for those models. The short frame models were not introduced for the Gen 4 and Gen 5 models, as the replaceable backstraps design makes a separate short frame version redundant.

Glock also produces single-stack "slimline" models, targeting the concealed carry market. The first was introduced with Gen 3 in .45 ACP as the Glock 36. More recently, after the introduction of Gen 5, came the Glock 42 in .380 ACP, followed by the Glock 43 in 9mm Parabellum. The most recent additions to the "slimline" series, the 43X and 48, were introduced together in 9mm Parabellum. These have longer grips that allow for a full three-finger hold and a 10-round capacity. The 43X is a long grip "crossover" 43, while the 48 has a longer slide to provide a "slimline" version of the "compact" Glock 19.

Glock Variants with normal frame width (slide size/grip size)

Caliber	Subcompact (SC)/SC	Compact (C)/C	C/Standard (Std)	Std/C	Std/Std	Competition/Std	Long Slide/Std
9×19mm	G26	G19, G46	G19X, G45	G49	G17, G18, G47, P80	G34	G17L
10mm Auto	G29				G20		G40
.45 ACP	G30, G30S				G21	G41
.40 S&W	G27	G23			G22	G35	G24
.380 Auto	G28	G25
.357 SIG	G33	G32			G31
.45 G.A.P.	G39	G38			G37
22 LR		G44