Glock The Glock pistol , sometimes referred to by the manufacturer as " Glock " Safe Action " Pistol " , is a series of semi - automatic pistol s designed and produced by Glock Ges . m . b . H . , located in Deutsch - Wagram , Austria . The company ' s founder , engineer Gaston Glock , had no experience with firearm design or manufacture at the time their first pistol , the " Glock 17 " , was being prototyped . Glock did , however , have extensive experience in advanced synthetic polymers , knowledge of which was instrumental in the company ' s design of the first successful line of pistols with a polymer frame . Glock introduced ferritic nitrocarburizing into the firearms industry as an anti - corrosion surface treatment for metal gun parts . Despite initial resistance from the market to accept a " plastic gun " due to durability and reliability concerns , and fears that the pistol would be " invisible " to metal detectors in airports , Glock pistols have become the company ' s most profitable line of products , commanding 65 % of the market share of handguns for United States law enforcement agencies as well as supplying numerous national armed forces and security agencies worldwide . Glocks are also popular weapons amongst civilians for home / self defense and concealed / open carry . History . Development . In 1980 , the Austrian military announced that it would seek tenders for a new , modern duty pistol to replace their World War II - era Walther P38 handguns . The Austrian Ministry of Defence formulated a list of 17 criteria for the new generation service pistol : 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 developed a working prototype . The new weapon made extensive use of synthetic materials and modern manufacturing technologies in its design , making it a very cost - effective candidate . Several samples of the 9×19mm Glock 17 ( so named because it was the 17th set of technical drawings of the company ) were submitted for assessment trials in early 1982 , and after passing all of the exhaustive endurance and abuse tests , Glock emerged as the winner with the Model 17 . The handgun was adopted into service with the Austrian military and police forces in 1982 as the P80 ( " Pistole 80 " ) , with an initial order for 25 , 000 guns . The Glock 17 outperformed 8 different pistols from five other established manufacturers ( Heckler & Koch of Germany offered their P7M8 , P7M13 and P9S , SIG Sauer of Germany bid with their P220 and P226 models , Beretta of Italy submitted their model 92SB - F , FN Herstal proposed an updated variant of the Browning Hi - Power and the home - grown Steyr 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 ongoing 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 . Shortly thereafter , the Glock 17 was accepted into service with the Norwegian , and Swedish Armed Forces , surpassing 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 . Product evolution . Glock has updated its basic design several times throughout its production history . Commentators had long separated the large changes into generations . Glock eventually accepted this nomenclature with their " Gen4 " models . Second generation models . A mid - life upgrade to the Glock pistols involved the addition of checkering on the front strap and serrations to the back strap . These versions were introduced in 1988 and were informally referred to as " second generation " models . To meet American ATF regulations , a steel plate with a stamped serial number was embedded into the receiver in front of the trigger guard . 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 . In the late 1990s , the frame was further modified with an accessory rail ( called the " Universal Glock rail " ) to allow the mounting of laser sights , tactical light s , and other accessories . Thumb rests on both sides of the frame and finger grooves on the front strap were added . 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 forces exerted by the locking block . This cross pin is known as the locking block pin and 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 ( " 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 a new checkering texture around the grip and new scalloped ( fish gill shaped ) serrations at the rear of the sides of the slide . Fourth Generation models . 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 fourth generation models do not have total parts modularity with its predecessors , meaning not all parts can be mixed and matched with previous Glock generations . The initial two fourth generation models announced were the full - size 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 texture frame , grip checkering , and interchangeable backstraps of different sizes . " 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 compared to the previous design . A punch is provided to remove the standard trigger housing pin and replace it for the longer cross pin needed to mount the medium or large backstrap . With the medium backstrap installed , the grip size is comparable to the third generation pistols . The magazine release catches are enlarged and reversible for left - handed use . To utilize the exchangeable magazine release feature , fourth generation Glock magazines have two notches cut on both sides of the magazine body . Mechanically , fourth generation Glock pistols are fitted with a dual recoil spring assembly to help reduce perceived recoil and increase service life expectancy . Earlier subcompact Glock models such as the Glock 26 and Glock 30 have 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 , in order 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 offers to exchange the recoil spring assemblies of its fourth generation pistols ( with the exception of the " subcompact " Glock 26 and Glock 27 models ) sold before 22 July 2011 at no cost “ in order to ensure our products perform up to GLOCK ’ s stringent standards , ” according to the company . Design details . Operating mechanism . The Glock 17 is a 9mm 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 utilizes a linkless , vertically tilting barrel with a rectangular breech that locks into the ejection port cut - out in the slide . During the recoil stroke , the barrel moves rearward initially locked together with the slide approximately until the bullet leaves the barrel and 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 . Features . The slide features a spring - loaded claw extractor and the stamped sheet metal ejector is pinned to the subframe . Post 2002 pistols 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 , powered by the firing pin spring . When the pistol is charged , the firing pin is in the half - cock position . As the trigger is pulled , the striker is then fully cocked . At the end of its travel , the trigger bar is tilted downward by the disconnector , releasing the striker to fire the cartridge . The disconnector resets the trigger bar so that the striker will be captured in half - cock at the end of the firing cycle . This is known as a pre - set trigger mechanism , referred to as the " Safe Action " trigger by the manufacturer . The disconnector ensures the pistol can only fire semi - automatically . The factory - standard two - stage trigger has a trigger travel of and is rated at , but by using a modified connector it can be increased to or lowered to . In response to a request made by 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 to and to respectively , which require approximately to of force to disengage the safeties and another to 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 and 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 a non - slip , 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 , which is secured from unintentional manipulation by a raised guard molded into the frame . The Glock pistol has a relatively low slide profile , which holds the barrel axis close to the shooter ' s hand and makes the pistol more comfortable to shoot by reducing muzzle rise and allows for faster aim recovery in rapid shooting sequence . The rectangular slide is milled from a single block of ordnance - grade steel using CNC machinery . The barrel and slide undergo two hardening processes prior to treatment with a proprietary nitriding process called Tenifer . The Tenifer treatment is applied in a 500 °C nitrate bath . The Tenifer finish is between and 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 , non - glare 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 better endure the effects of perspiration . Glock steel parts having the Tenifer treatment are more corrosion - resistant than analogous gun parts having other finishes or treatments , including Teflon , bluing , hard chrome plating , or phosphates . After applying the Tenifer process , a black Parkerized decorative surface finish is applied . The underlaying Tenifer treatment will remain protecting these parts even if the decorative surface finish were to wear off . A current production 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 pistol cartridge , but can use high - power ( increased pressure ) + P and + 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 non - circular segments ( only the . 45ACP and . 45GAP 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 . The method by which Glock barrels are rifled is somewhat unusual ; instead of using a traditional broaching machine to cut the rifling into the bore , the Glock process involves beating a slowly rotating mandrel through the bore to obtain the hexagon al or octagon al 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 around 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 , increased accuracy and ease of maintenance . Safety . Glock 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 for firing only when the trigger is actuated and the safety is pushed up through 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 . This passive safety system omits the manipulation of traditional on - off levers , hammers or other external safeties as found in many other handgun designs . In 2003 , Glock announced the Internal Locking System ( ILS ) safety feature . The ILS is a manually activated lock that is 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 giving both a visual and tactile indication as to whether the lock is engaged or not . 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 . Feeding . The Glock 17 feeds from staggered - column or double stack magazine s that have a 17 - round capacity ( which can be extended to 19 with an optional floor plate ) or optional 33 - round high capacity magazines . For jurisdictions which 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 shooting hand . Glock magazines are interchangeable between models , 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 . Sights . 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 . The rear sight can be adjusted for windage ( on certain models due to the windage sights not coming as factory default ) , as it has a degree of lateral movement in the dovetail it is mounted in . Three other factory rear sight configurations are available in addition to the standard height sight : a lower impact sight and two higher impact versions – and . 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 alternate version of the tactical light utilizing an invisible infrared light and laser sight is available , designed to be used with an infrared night vision device . Another lighting accessory is an adapter to mount a flashlight onto 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 underwater spring cups . Magazine floor plates ( or " + 2 baseplates " ) , which expand the capacity of the standard magazines by 2 rounds are available for models chambered for the 9×19mm Parabellum , . 40 S & W , . 357 SIG , and . 380 ACP cartridges . In addition to the standard non - adjustable polymer sight line , three alternative sight lines are offered by Glock . These consist of steel , adjustable and self - illuminating tritium night rear sights and factory steel and self - illuminating tritium contrast pointer steel front sights . Variants . Following the introduction of the Glock 17 , numerous variants and versions have been offered . Variants that differ in caliber , frame , and slide length are identified by different model numbers with the exception of the discontinued Glock 17L . Other changes not dealing with frame and slide length are identified with suffixes , such as " C " , which denotes compensated models . Minor options such as frame color , sights , and included accessories are identified by a separate model code on the box and do not appear anywhere on the firearm . Glock pistols come in five form factors , all modeled after the original full - size Glock 17 . " Standard " models are designed as full - size duty firearm 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 being lighter and shorter , and are intended to be used with two fingers on the grip below the trigger guard and do not feature an accessory rail like the larger post generation two Glock models . . 45 ACP and 10mm models have bigger , wider slides and are slightly larger than the smaller chambered pistols and are available in the sub - compact models Glock 29 ( 10mm ) and Glock 30 ( . 45ACP ) . Glock produces a single - stack " Slimline " . 45 ACP pistol , the Glock 36 . " Competition " versions have longer barrels and slides , adjustable sights , an extended slide and magazine release . Beginning in 2007 , Glock introduced several " Short Frame " models designated by the suffix " SF " . The short frame was originally designed to compete in the now cancelled 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 MIL - STD - 1913 rail along with a reduction in the size of the backstrap . The Glock 21SF is currently available in three versions : one with a Picatinny rail and ambidextrous magazine release and two with a Universal Glock rail available with or without the ambidextrous magazine release . Current 10 mm and . 45 ACP Glock magazines are manufactured with ambidextrous magazine release cutouts . As of January 2009 , the Glock 20 , 21 , 29 , and 30 were offered in short - framed variations . These models incorporate a reduction in trigger reach , and full - sized models feature a reduction in heel depth . This reduction in heel depth corresponds to an overall reduction in length for those models . . 45 ACP . Glock pistols chambered for the . 45 ACP ( and the . 45 GAP ) feature octagon al polygonal rifling rather than the hexagonal shaped bores used for models in different chamberings . Octagonal rifling provides a better gas seal in relatively large diameter rifled bores , since an octagon resembles a circle more closely than a hexagon . . 40 S & W . As is typical of pistols chambered in . 40 S & W , each of the standard Glock models ( 22 , 23 , and 27 ) may be easily converted to the corresponding . 357 SIG chambering ( Glock 31 , 32 , and 33 respectively ) simply by replacing the barrel . No other parts need to be replaced , as the . 40 S & W magazines will feed the . 357 SIG round . . 380 ACP . The . 380 ACP models are primarily intended for markets which prohibit civilian ownership of firearms chambered in military calibers such as 9×19mm Parabellum . They are not offered in the United States , due to the characteristics of the gun making it unable to pass import restrictions . Due to the relatively low bolt thrust of the . 380 ACP cartridge , these models feature an unlocked breech and operates via straight blowback of the slide . This method of operation required modification of the locking surfaces on the barrel as well as a redesign of the former locking block . . 45 GAP . Glock pistols chambered for the . 45 GAP ( and the . 45 ACP ) feature octagon al polygonal rifling rather than the hexagonal shaped bores used for models in other chamberings . Octagonal rifling provides a better gas seal in relatively large diameter rifled bores , since an octagon resembles a circle more closely than a hexagon . Production in other countries . Aside from the original Austrian company , Glock pistols are manufactured in the division located in USA . Those batches are nearly the same and identical compared to the Austrian - made ones , but they have proof marks marked as " USA " , instead of " AUSTRIA " , on the slide . Glock 17 pistols are now to be assembled locally at army workshops of Uruguay to fulfill the needs of the national military services and LE organisations . These pistols are assembled initially with original Glock parts and later with locally manufactured parts . 205th Armory in Taiwan produces a copy of the Glock 19 , named as the T97 . The Taiwan - made Glocks were made to replace the Smith & Wesson Model 5906 used by the Taiwan police , but it ultimately did not enter service .