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138-406: Glock ( German: [ˈglɔk] ; stylized as GLOCK ) is a brand of polymer - framed , short-recoil -operated, striker-fired , locked-breech semi-automatic pistols designed and produced by Austrian manufacturer Glock Ges.m.b.H . The firearm entered Austrian military and police service in 1982 after becoming the top performer in reliability and safety tests. Glock pistols have become

276-769: A U-boat in 1942. After World War II, Beretta was actively involved in repairing the American M1 Garands that the U.S. had given Italy. Beretta modified the M1 into the Beretta BM-59 rifle, which is similar to the M14 battle rifle . Armourers consider the BM-59 rifle to be superior to the M14 rifle in some ways, because it is more accurate under certain conditions. After the war, Beretta continued to develop firearms for

414-459: A catalyst . Laboratory synthesis of biopolymers, especially of proteins , is an area of intensive research. There are three main classes of biopolymers: polysaccharides , polypeptides , and polynucleotides . In living cells, they may be synthesized by enzyme-mediated processes, such as the formation of DNA catalyzed by DNA polymerase . The synthesis of proteins involves multiple enzyme-mediated processes to transcribe genetic information from

552-441: A lower critical solution temperature phase transition (LCST), at which phase separation occurs with heating. In dilute solutions, the properties of the polymer are characterized by the interaction between the solvent and the polymer. In a good solvent, the polymer appears swollen and occupies a large volume. In this scenario, intermolecular forces between the solvent and monomer subunits dominate over intramolecular interactions. In

690-442: A metal detector . 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 fire by reducing muzzle rise and allows for faster aim recovery in rapid firing 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 prior to treatment with

828-418: A 17-round capacity (which can be extended to 19 with an optional floor plate) or optional 24 or 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

966-502: A bad solvent or poor solvent, intramolecular forces dominate and the chain contracts. In the theta solvent , or the state of the polymer solution where the value of the second virial coefficient becomes 0, the intermolecular polymer-solvent repulsion balances exactly the intramolecular monomer-monomer attraction. Under the theta condition (also called the Flory condition), the polymer behaves like an ideal random coil . The transition between

1104-454: 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. The locking block pin located above the trigger pin that was introduced in the third generation is omitted. Many internal parts were less conspicuously revised. "Gen 5"

1242-486: 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. Many of the existing models became available in

1380-503: A comparison microscope and an ABIS (Evofinder). Glock pistols lack a traditional on-off safety lever, which Glock markets as an advantage, especially to police departments, as the user is able to 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:

1518-527: A contract to Glock to provide new 9×19mm Parabellum chambered duty pistols. The solicitation specifications deviated from the specifications of Glock fourth-generation models. Features found in the M series pistols evolved into what 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

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1656-408: A degree of crystallinity approaching zero or one will tend to be transparent, while polymers with intermediate degrees of crystallinity will tend to be opaque due to light scattering by crystalline or glassy regions. For many polymers, crystallinity may also be associated with decreased transparency. The space occupied by a polymer molecule is generally expressed in terms of radius of gyration , which

1794-587: A deviation from a simple linear chain. A branched polymer molecule is composed of a main chain with one or more substituent side chains or branches. Types of branched polymers include star polymers , comb polymers , polymer brushes , dendronized polymers , ladder polymers , and dendrimers . There exist also two-dimensional polymers (2DP) which are composed of topologically planar repeat units. A polymer's architecture affects many of its physical properties including solution viscosity, melt viscosity, solubility in various solvents, glass-transition temperature and

1932-409: 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

2070-464: A flexible quality. Plasticizers are also put in some types of cling film to make the polymer more flexible. The attractive forces between polymer chains play a large part in determining the polymer's properties. Because polymer chains are so long, they have many such interchain interactions per molecule, amplifying the effect of these interactions on the polymer properties in comparison to attractions between conventional molecules. Different side groups on

2208-479: A given application, the properties of a polymer can be tuned or enhanced by combination with other materials, as in composites . Their application allows to save energy (lighter cars and planes, thermally insulated buildings), protect food and drinking water (packaging), save land and lower use of fertilizers (synthetic fibres), preserve other materials (coatings), protect and save lives (hygiene, medical applications). A representative, non-exhaustive list of applications

2346-434: 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 then be 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

2484-402: A high surface quality and are also highly transparent so that the laser properties are dominated by the laser dye used to dope the polymer matrix. These type of lasers, that also belong to the class of organic lasers , are known to yield very narrow linewidths which is useful for spectroscopy and analytical applications. An important optical parameter in the polymer used in laser applications

2622-406: 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). 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

2760-665: 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 better endure the effects of perspiration. 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

2898-545: 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

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3036-447: 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 compared to the previous design. A punch is provided to remove the standard trigger housing pin and replace it with

3174-502: A notch cut on both sides of the magazine body. Earlier versions of the magazines will not lock into the Gen4 pistols if the user has moved the magazine release button 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 help reduce perceived recoil and increase service life expectancy. Earlier subcompact Glock models such as

3312-435: 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

3450-401: A polymer behaves as a continuous macroscopic material. They are classified as bulk properties, or intensive properties according to thermodynamics . The bulk properties of a polymer are those most often of end-use interest. These are the properties that dictate how the polymer actually behaves on a macroscopic scale. The tensile strength of a material quantifies how much elongating stress

3588-421: A polymer is its first and most important attribute. Polymer nomenclature is generally based upon the type of monomer residues comprising the polymer. A polymer which contains only a single type of repeat unit is known as a homopolymer , while a polymer containing two or more types of repeat units is known as a copolymer . A terpolymer is a copolymer which contains three types of repeat units. Polystyrene

3726-433: A polymeric material can be described at different length scales, from the sub-nm length scale up to the macroscopic one. There is in fact a hierarchy of structures, in which each stage provides the foundations for the next one. The starting point for the description of the structure of a polymer is the identity of its constituent monomers. Next, the microstructure essentially describes the arrangement of these monomers within

3864-536: A process called reptation in which each chain molecule is constrained by entanglements with neighboring chains to move within a virtual tube. The theory of reptation can explain polymer molecule dynamics and viscoelasticity . Depending on their chemical structures, polymers may be either semi-crystalline or amorphous. Semi-crystalline polymers can undergo crystallization and melting transitions , whereas amorphous polymers do not. In polymers, crystallization and melting do not suggest solid-liquid phase transitions, as in

4002-430: 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

4140-519: 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 "to ensure our products perform up to GLOCK's stringent standards", according to the company. On 29 June 2016, the United States Federal Bureau of Investigation (FBI) awarded

4278-427: A result, they typically have lower melting temperatures than other polymers. When a polymer is dispersed or dissolved in a liquid, such as in commercial products like paints and glues, the chemical properties and molecular interactions influence how the solution flows and can even lead to self-assembly of the polymer into complex structures. When a polymer is applied as a coating, the chemical properties will influence

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4416-456: A statistical distribution of chain lengths, the molecular weight is expressed in terms of weighted averages. The number-average molecular weight ( M n ) and weight-average molecular weight ( M w ) are most commonly reported. The ratio of these two values ( M w / M n ) is the dispersity ( Đ ), which is commonly used to express the width of the molecular weight distribution. The physical properties of polymer strongly depend on

4554-537: A tendency to form amorphous and semicrystalline structures rather than crystals . Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer physics ), biophysics and materials science and engineering . Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science. An emerging important area now focuses on supramolecular polymers formed by non-covalent links. Polyisoprene of latex rubber

4692-432: A variety of different but structurally related monomer residues; for example, polynucleotides such as DNA are composed of four types of nucleotide subunits. A polymer containing ionizable subunits (e.g., pendant carboxylic groups ) is known as a polyelectrolyte or ionomer , when the fraction of ionizable units is large or small respectively. The microstructure of a polymer (sometimes called configuration) relates to

4830-403: 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 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 6.5 mm (0.26 in) height sight:

4968-405: A wide-meshed cross-linking between the "main chains". Close-meshed crosslinking, on the other hand, leads to thermosets . Cross-links and branches are shown as red dots in the figures. Highly branched polymers are amorphous and the molecules in the solid interact randomly. An important microstructural feature of a polymer is its architecture and shape, which relates to the way branch points lead to

5106-528: 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 moves rearward initially locked together with

5244-814: Is a substance or material that consists of very large molecules, or macromolecules , that are constituted by many repeating subunits derived from one or more species of monomers . Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers . Their consequently large molecular mass , relative to small molecule compounds , produces unique physical properties including toughness , high elasticity , viscoelasticity , and

5382-479: Is a crucial physical parameter for polymer manufacturing, processing, and use. Below T g , molecular motions are frozen and polymers are brittle and glassy. Above T g , molecular motions are activated and polymers are rubbery and viscous. The glass-transition temperature may be engineered by altering the degree of branching or crosslinking in the polymer or by the addition of plasticizers . Whereas crystallization and melting are first-order phase transitions ,

5520-410: Is a long-chain n -alkane. There are also branched macromolecules with a main chain and side chains, in the case of polyethylene the side chains would be alkyl groups . In particular unbranched macromolecules can be in the solid state semi-crystalline, crystalline chain sections highlighted red in the figure below. While branched and unbranched polymers are usually thermoplastics, many elastomers have

5658-400: Is also commonly present in polymer backbones, such as those of polyethylene glycol , polysaccharides (in glycosidic bonds ), and DNA (in phosphodiester bonds ). Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network. During the polymerization process, some chemical groups may be lost from each monomer. This happens in

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5796-512: Is an average distance from the center of mass of the chain to the chain itself. Alternatively, it may be expressed in terms of pervaded volume , which is the volume spanned by the polymer chain and scales with the cube of the radius of gyration. The simplest theoretical models for polymers in the molten, amorphous state are ideal chains . Polymer properties depend of their structure and they are divided into classes according to their physical bases. Many physical and chemical properties describe how

5934-481: Is an example of a natural polymer, and the polystyrene of styrofoam is an example of a synthetic polymer. In biological contexts, essentially all biological macromolecules —i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides —are purely polymeric, or are composed in large part of polymeric components. The term "polymer" derives from Greek πολύς (polus)  'many, much' and μέρος (meros)  'part'. The term

6072-428: Is composed only of styrene -based repeat units, and is classified as a homopolymer. Polyethylene terephthalate , even though produced from two different monomers ( ethylene glycol and terephthalic acid ), is usually regarded as a homopolymer because only one type of repeat unit is formed. Ethylene-vinyl acetate contains more than one variety of repeat unit and is a copolymer. Some biological polymers are composed of

6210-409: Is defined, for small strains , as the ratio of rate of change of stress to strain. Like tensile strength, this is highly relevant in polymer applications involving the physical properties of polymers, such as rubber bands. The modulus is strongly dependent on temperature. Viscoelasticity describes a complex time-dependent elastic response, which will exhibit hysteresis in the stress-strain curve when

6348-692: Is given below. Beretta Val Trompia , a northern Italian river valley in the Province of Brescia , Lombardy , has been mined for iron ore since the time of the Roman Empire . In the Middle Ages , Val Trompia was known for its ironworks; after the Renaissance it came to be a center for the manufacture of weapons. By the mid 16th century Val Trompia had forty ironworks, supplied by fifty mines and eight smelters. The birthplace of Beretta

6486-648: Is in the village of Gardone , located on the banks of the Mella river in the middle of Val Trompia (i.e., between the upper and lower valley). The Beretta forge was in operation from about 1500, although the first documented transaction is a contract dated October 3, 1526, for 185 arquebus barrels, for which the Republic of Venice was to pay 296 ducats to Maestro di Canne (master gun-barrel maker) Bartolomeo Beretta (in Italian) . The original account document for

6624-455: 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

6762-401: 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

6900-461: 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 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

7038-481: 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. 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

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7176-482: Is rollmarked on the slide next to the model number to identify the fifth-generation pistols. The "Gen 5" slide can feature front serrations (FS) to provide an additional tactile traction surface choice. The magazines were also revised for the fifth-generation models: the redesigned magazine floor plates feature a frontward protruding lip to offer grip for manual assisted extraction and the magazine follower became orange colored for easier visual identification. The Glock 17

7314-853: Is run by Franco Gussalli Beretta, President and CEO. The traditional father-to-son Beretta dynasty was interrupted when Ugo Gussalli Beretta assumed the firm's control; uncles Carlo and Giuseppe Beretta were childless; Ugo married into the Beretta family and adopted the last name Beretta. His sons are now direct descendants through their mother's side of the family. Beretta is known for its broad range of firearms: side-by-side shotguns , over-and-under shotguns, semi-automatic shotguns, hunting rifles , express rifles , assault rifles , submachine guns , lever- and bolt-action rifles, single- and double-action revolvers and semi-automatic pistols . The parent company, Beretta Holding, also owns Beretta USA, Benelli , Franchi , SAKO , Stoeger , Tikka , Uberti , and

7452-435: Is the change in refractive index with temperature also known as dn/dT. For the polymers mentioned here the (dn/dT) ~ −1.4 × 10 in units of K in the 297 ≤ T ≤ 337 K range. Most conventional polymers such as polyethylene are electrical insulators , but the development of polymers containing π-conjugated bonds has led to a wealth of polymer-based semiconductors , such as polythiophenes . This has led to many applications in

7590-563: Is the main constituent of wood and paper. Hemoglycin (previously termed hemolithin ) is a space polymer that is the first polymer of amino acids found in meteorites . The list of synthetic polymers , roughly in order of worldwide demand, includes polyethylene , polypropylene , polystyrene , polyvinyl chloride , synthetic rubber , phenol formaldehyde resin (or Bakelite ), neoprene , nylon , polyacrylonitrile , PVB , silicone , and many more. More than 330 million tons of these polymers are made every year (2015). Most commonly,

7728-712: The 1943 Armistice between Italy and the Allied forces during World War II . Once the Wehrmacht controlled northern Italy, the Germans seized Beretta and continued using it to produce arms until the 1945 German surrender in Italy. During that time, the quality of the exterior finish of the weapons diminished—-late-war specimens were much inferior to both the pre-war and mid-war weapons—-but their efficacy remained excellent. The last shipment of Type I Rifles left Venice for Japan in

7866-645: 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 were not to require any means of assistance for loading; be secure against accidental discharge from shock, strike, and drop from

8004-551: 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

8142-925: 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,

8280-679: 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,

8418-452: The "fifth generation" or "Gen 5". 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,

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8556-858: 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

8694-633: The Burris Optics company. The model Beretta 92FS was the primary side arm of the United States Army , Marine Corps , Navy and Air Force , designated the M9 pistol . In 1985, Beretta was chosen after a controversial competition to produce the M9, winning a contract for 500,000 pistols. A condition of the original agreement was domestic manufacture of the M9. In 2019, the 9mm version of

8832-545: The DNA to RNA and subsequently translate that information to synthesize the specified protein from amino acids . The protein may be modified further following translation in order to provide appropriate structure and functioning. There are other biopolymers such as rubber , suberin , melanin , and lignin . Naturally occurring polymers such as cotton , starch , and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on

8970-622: The Flux Defense Brace. A Glock switch is an aftermarket accessory which depresses the firearm's sear , allowing fully automatic fire. Without the proper license , they are illegal in the United States. Polymer A polymer is a substance composed of macromolecules. A macromolecule is a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass. A polymer ( / ˈ p ɒ l ɪ m ər / )

9108-404: 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, and after passing all of the exhaustive endurance and abuse tests, the Glock emerged as the winner. According to Friedrich Dechant, former head of

9246-611: 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

9384-486: 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. In September 2011, Glock announced

9522-553: The Glock 26 and Glock 30 have already used a dual recoil spring assembly that 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

9660-408: The Glock pistols involved the addition of checkering on the front strap and trigger guard and checkering and serrations to the back strap. These versions, introduced in 1988, were informally referred to as "second-generation" or Gen2 models, though 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

9798-486: The Glock third- and fourth-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." In August 2017, Glock presented

9936-541: 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. The Glock 17 feeds from staggered-column or double stack magazines that have

10074-480: 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, giving both a visual and tactile indication as to whether the lock is engaged or not. When activated,

10212-643: The Italian army and police force, as well as the civilian market. In the 1970s, Beretta also started a manufacturing plant in São Paulo , Brazil . A contract between Beretta and the Brazilian government was signed, under which Beretta produced Beretta 92s for the Brazilian Army until 1980. Later this plant was sold to Taurus , who continues to manufacture the Beretta 92 under the name of PT92 using

10350-793: 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. Glock has updated its basic design several times throughout its production history. The first-generation (Gen 1) Glock pistols are most notably recognized by their smoother "pebble finish" grip and finger groove-less frames. The Gen 1 frame pattern and design

10488-530: The RTF2   version, including the 17, 31, 32, 23, 21, and 19. Some of those did not have the fish gills. 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

10626-687: 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". These early Glock   17 "pencil barrel" pistols are considered rare and highly desirable by Glock collectors. The barrels were later redesigned with thicker bore walls, and manufacturing continued to evolve and improve

10764-724: 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 M 9A1 of which 19 pistols each, all chambered in 9×19   mm   Parabellum, were entered in

10902-560: 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 in order to meet the ATF's importation requirements, and so it was dubbed the "weekend" sight. These first-generation adjustable rear sights extended past

11040-564: The United States. In actuality, 84% of the gun's weight is from steel, and Polymer 2 is visible to X-ray machines. The myth's prevalence is believed to be connected to a scene that perpetuated the myth in Die Hard 2 , which released a few years after the Glock was invented. In 1988, the Undetectable Firearms Act was passed in the United States, banning the manufacture or import of any gun that could pass undetected through

11178-552: The Venetian Republic in 1797. Beretta has been owned by the same family for almost five hundred years; it is a founding member of Les Henokiens , an association of bicentenary companies that are family owned and operated. In 1918, the Beretta Model 1918 , one of the first submachine guns in the world, was fielded by the Italian army. Beretta manufactured rifles and pistols for the Italian military until

11316-441: The adhesion of the coating and how it interacts with external materials, such as superhydrophobic polymer coatings leading to water resistance. Overall the chemical properties of a polymer are important elements for designing new polymeric material products. Polymers such as PMMA and HEMA:MMA are used as matrices in the gain medium of solid-state dye lasers , also known as solid-state dye-doped polymer lasers. These polymers have

11454-434: The backbone in a variety of ways. A copolymer containing a controlled arrangement of monomers is called a sequence-controlled polymer . Alternating, periodic and block copolymers are simple examples of sequence-controlled polymers . Tacticity describes the relative stereochemistry of chiral centers in neighboring structural units within a macromolecule. There are three types of tacticity: isotactic (all substituents on

11592-526: 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. 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

11730-421: The case of water or other molecular fluids. Instead, crystallization and melting refer to the phase transitions between two solid states ( i.e. , semi-crystalline and amorphous). Crystallization occurs above the glass-transition temperature ( T g ) and below the melting temperature ( T m ). All polymers (amorphous or semi-crystalline) go through glass transitions . The glass-transition temperature ( T g )

11868-488: 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,

12006-442: The company's most profitable line of products, and have been supplied to national armed forces, security agencies, and police forces in at least 48 countries. Glocks are also popular firearms among civilians for recreational and competition shooting , home- and self-defense, both in concealed or open carry . The company's founder and head engineer, Gaston Glock (1929–2023), had no experience with firearms design or manufacture at

12144-476: The continuously linked backbone of a polymer used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene ('polythene' in British English), whose repeat unit or monomer is ethylene . Many other structures do exist; for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen

12282-536: The degree of crystallinity may be expressed in terms of a weight fraction or volume fraction of crystalline material. Few synthetic polymers are entirely crystalline. The crystallinity of polymers is characterized by their degree of crystallinity, ranging from zero for a completely non-crystalline polymer to one for a theoretical completely crystalline polymer. Polymers with microcrystalline regions are generally tougher (can be bent more without breaking) and more impact-resistant than totally amorphous polymers. Polymers with

12420-418: 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. This box design was later changed by Glock to meet BATF import requirements, and the ammunition storage compartments were removed. A mid-life upgrade to

12558-400: The driving force for mixing is usually entropy , not interaction energy. In other words, miscible materials usually form a solution not because their interaction with each other is more favorable than their self-interaction, but because of an increase in entropy and hence free energy associated with increasing the amount of volume available to each component. This increase in entropy scales with

12696-417: The field of organic electronics . Nowadays, synthetic polymers are used in almost all walks of life. Modern society would look very different without them. The spreading of polymer use is connected to their unique properties: low density, low cost, good thermal/electrical insulation properties, high resistance to corrosion, low-energy demanding polymer manufacture and facile processing into final products. For

12834-432: 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 as the "Safe action" trigger by the manufacturer. The connector ensures the pistol can only fire semiautomatically. The factory-standard, two-stage trigger has a trigger travel of 12.5 mm (0.49 in) and

12972-527: The free energy of mixing for polymer solutions and thereby making solvation less favorable, and thereby making the availability of concentrated solutions of polymers far rarer than those of small molecules. Furthermore, the phase behavior of polymer solutions and mixtures is more complex than that of small molecule mixtures. Whereas most small molecule solutions exhibit only an upper critical solution temperature phase transition (UCST), at which phase separation occurs with cooling, polymer mixtures commonly exhibit

13110-401: The glass transition is not. The glass transition shares features of second-order phase transitions (such as discontinuity in the heat capacity, as shown in the figure), but it is generally not considered a thermodynamic transition between equilibrium states. In general, polymeric mixtures are far less miscible than mixtures of small molecule materials. This effect results from the fact that

13248-415: The individual chains more strongly in position and resist deformations and matrix breakup, both at higher stresses and higher temperatures. Copolymers are classified either as statistical copolymers, alternating copolymers, block copolymers, graft copolymers or gradient copolymers. In the schematic figure below, Ⓐ and Ⓑ symbolize the two repeat units . Monomers within a copolymer may be organized along

13386-451: The latter case, increasing the polymer chain length 10-fold would increase the viscosity over 1000 times. Increasing chain length furthermore tends to decrease chain mobility, increase strength and toughness, and increase the glass-transition temperature (T g ). This is a result of the increase in chain interactions such as van der Waals attractions and entanglements that come with increased chain length. These interactions tend to fix

13524-436: The length (or equivalently, the molecular weight) of the polymer chain. One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. The influence of the weight-average molecular weight ( M w {\displaystyle M_{w}} ) on the melt viscosity ( η {\displaystyle \eta } ) depends on whether

13662-417: The load is removed. Dynamic mechanical analysis or DMA measures this complex modulus by oscillating the load and measuring the resulting strain as a function of time. Transport properties such as diffusivity describe how rapidly molecules move through the polymer matrix. These are very important in many applications of polymers for films and membranes. The movement of individual macromolecules occurs by

13800-428: 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 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

13938-436: The market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur . Ways in which polymers can be modified include oxidation , cross-linking , and end-capping . The structure of

14076-413: The material will endure before failure. This is very important in applications that rely upon a polymer's physical strength or durability. For example, a rubber band with a higher tensile strength will hold a greater weight before snapping. In general, tensile strength increases with polymer chain length and crosslinking of polymer chains. Young's modulus quantifies the elasticity of the polymer. It

14214-476: The newer GMB ones are designed differently. A study by Stephen Christen and Hans Rudolf Jordi, published by Forensic Science International in February 2019, shows that the new GMB barrels leave more identifiably unique 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

14352-444: The number of particles (or moles) being mixed. Since polymeric molecules are much larger and hence generally have much higher specific volumes than small molecules, the number of molecules involved in a polymeric mixture is far smaller than the number in a small molecule mixture of equal volume. The energetics of mixing, on the other hand, is comparable on a per volume basis for polymeric and small molecule mixtures. This tends to increase

14490-776: The order of those barrels is now stored in the Archivio di Stato di Venezia (in Italian) in Venice . By the end of the 17th century, Beretta had become the second largest gun barrel maker in Gardone. Under the guild system, the knowledge of gun barrel fabrication that had been bequeathed to Jacopo (1520/25 – …) by his father Bartolomeo (1490 – 1565/68) was then passed down to Jacopo’s own son, Giovannino (1550 – post 1577), and then to his grandson Giovan Antonio (1577 – post 1649), and it continued to be passed down in this manner until guilds were abolished by Napoleon after his conquest of

14628-719: The partially negatively charged oxygen atoms in C=O groups on another. These strong hydrogen bonds, for example, result in the high tensile strength and melting point of polymers containing urethane or urea linkages. Polyesters have dipole-dipole bonding between the oxygen atoms in C=O groups and the hydrogen atoms in H-C groups. Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than Kevlar 's ( Twaron ), but polyesters have greater flexibility. Polymers with non-polar units such as polyethylene interact only through weak Van der Waals forces . As

14766-422: The physical arrangement of monomer residues along the backbone of the chain. These are the elements of polymer structure that require the breaking of a covalent bond in order to change. Various polymer structures can be produced depending on the monomers and reaction conditions: A polymer may consist of linear macromolecules containing each only one unbranched chain. In the case of unbranched polyethylene, this chain

14904-493: 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 into 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

15042-399: The polymer and create gaps between polymer chains for greater mobility and fewer interchain interactions. A good example of the action of plasticizers is related to polyvinylchlorides or PVCs. A uPVC, or unplasticized polyvinylchloride, is used for things such as pipes. A pipe has no plasticizers in it, because it needs to remain strong and heat-resistant. Plasticized PVC is used in clothing for

15180-426: The polymer at the scale of a single chain. The microstructure determines the possibility for the polymer to form phases with different arrangements, for example through crystallization , the glass transition or microphase separation . These features play a major role in determining the physical and chemical properties of a polymer. The identity of the repeat units (monomer residues, also known as "mers") comprising

15318-543: The polymer can lend the polymer to ionic bonding or hydrogen bonding between its own chains. These stronger forces typically result in higher tensile strength and higher crystalline melting points. The intermolecular forces in polymers can be affected by dipoles in the monomer units. Polymers containing amide or carbonyl groups can form hydrogen bonds between adjacent chains; the partially positively charged hydrogen atoms in N-H groups of one chain are strongly attracted to

15456-403: The polymer is above or below the onset of entanglements . Below the entanglement molecular weight , η ∼ M w 1 {\displaystyle \eta \sim {M_{w}}^{1}} , whereas above the entanglement molecular weight, η ∼ M w 3.4 {\displaystyle \eta \sim {M_{w}}^{3.4}} . In

15594-583: The polymerization of PET polyester . The monomers are terephthalic acid (HOOC—C 6 H 4 —COOH) and ethylene glycol (HO—CH 2 —CH 2 —OH) but the repeating unit is —OC—C 6 H 4 —COO—CH 2 —CH 2 —O—, which corresponds to the combination of the two monomers with the loss of two water molecules. The distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Synthetic methods are generally divided into two categories, step-growth polymerization and chain polymerization . The essential difference between

15732-451: 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

15870-432: 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:

16008-437: The same side), atactic (random placement of substituents), and syndiotactic (alternating placement of substituents). Polymer morphology generally describes the arrangement and microscale ordering of polymer chains in space. The macroscopic physical properties of a polymer are related to the interactions between the polymer chains. When applied to polymers, the term crystalline has a somewhat ambiguous usage. In some cases,

16146-559: The same tools and labour which Beretta used, without the need for a license from Beretta, since the design is based on the original Beretta 92, for which the patents have expired. In the late 1980s, Beretta acquired several domestic competitors (notably Benelli and Franchi ) and some foreign companies (notably in Finland). Also in the 1980s, Beretta enjoyed a renewal of popularity in North America, after its Beretta 92 pistol

16284-549: 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

16422-512: The size of individual polymer coils in solution. A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, for example living polymerization . A common means of expressing the length of a chain is the degree of polymerization , which quantifies the number of monomers incorporated into the chain. As with other molecules, a polymer's size may also be expressed in terms of molecular weight . Since synthetic polymerization techniques typically yield

16560-418: The slide about 3 mm (0.12 in) 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

16698-465: 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. The first Glock pistols sent to

16836-454: 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 –

16974-519: 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

17112-427: 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

17250-481: The spent cartridge casing. The slide's uninterrupted rearward movement and counter-recoil cycle are characteristic of the Browning system. Glock pistols incorporate a number of features intended to enhance reliability in adverse conditions, such as utilizing advanced metal coatings, "stub" slide guides instead of true frame rails, and an unusual cocking mechanism wherein the trigger is partially responsible for cocking

17388-516: The standard nonadjustable 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. 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

17526-448: The states is known as a coil–globule transition . Inclusion of plasticizers tends to lower T g and increase polymer flexibility. Addition of the plasticizer will also modify dependence of the glass-transition temperature T g on the cooling rate. The mobility of the chain can further change if the molecules of plasticizer give rise to hydrogen bonding formation. Plasticizers are generally small molecules that are chemically similar to

17664-403: 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, whereas almost all other striker-fired pistols on the market rely fully on the recoil spring to cock the striker. The slide features a spring-loaded claw extractor , and the stamped sheet metal ejector

17802-498: The tactical light using 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 maritime spring cups. Maritime spring cups are designed to allow

17940-686: The term crystalline finds identical usage to that used in conventional crystallography . For example, the structure of a crystalline protein or polynucleotide, such as a sample prepared for x-ray crystallography , may be defined in terms of a conventional unit cell composed of one or more polymer molecules with cell dimensions of hundreds of angstroms or more. A synthetic polymer may be loosely described as crystalline if it contains regions of three-dimensional ordering on atomic (rather than macromolecular) length scales, usually arising from intramolecular folding or stacking of adjacent chains. Synthetic polymers may consist of both crystalline and amorphous regions;

18078-400: The time 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. In 1980,

18216-459: 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

18354-427: 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. In 2003, Glock announced

18492-555: The two is that in chain polymerization, monomers are added to the chain one at a time only, such as in polystyrene , whereas in step-growth polymerization chains of monomers may combine with one another directly, such as in polyester . Step-growth polymerization can be divided into polycondensation , in which low-molar-mass by-product is formed in every reaction step, and polyaddition . Newer methods, such as plasma polymerization do not fit neatly into either category. Synthetic polymerization reactions may be carried out with or without

18630-605: Was coined in 1833 by Jöns Jacob Berzelius , though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger , who spent the next decade finding experimental evidence for this hypothesis. Polymers are of two types: naturally occurring and synthetic or man made . Natural polymeric materials such as hemp , shellac , amber , wool , silk , and natural rubber have been used for centuries. A variety of other natural polymers exist, such as cellulose , which

18768-399: Was selected as the service handgun for the United States Army (as the " M9 pistol "). In 1993, a Beretta USA executive revealed that it had been the company's strategy since 1980 "to use the military contract to make Beretta a household name in the United States", and then to expand into larger law enforcement and commercial markets. Today , Fabbrica d'Armi Pietro Beretta (Beretta S.p.A.)

18906-570: Was slightly modified, changing the floorplate and fitting the follower spring with a resistance insert at its base. 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 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

19044-438: 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

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