The G3 is a 7.62mm battle rifle developed in the 1950s by the German armament manufacturer Heckler & Koch GmbH (H&K) in collaboration with the Spanish state-owned design and development agency CETME (Centro de Estudios Técnicos de Materiales Especiales).

History.

The origin of this rifle can be traced back to the final years of World War II when Mauser engineers at the Light Weapon Development Group (Abteilung 37) at Oberndorf am Neckar designed the MKb Gerät 06 (Maschinenkarabiner Gerät 06 or "machine carbine device 06") prototype assault rifle chambered for the intermediate 7.92×33mm Kurz cartridge, first with the Gerät 06 model using a roller-locked short recoil mechanism originally adapted from the MG 42 machine gun but with a fixed barrel and conventional gas-actuated piston rod.[2] It was realized that with careful attention to the mechanical ratios, the gas system could be omitted.[3] The resultant weapon, the Gerät 06H (the "H" suffix is an abbreviation for halbverriegelt or "half-locked") was assigned the designation StG 45(M) (Sturmgewehr 45(M) or assault rifle) but was not produced in any significant numbers and the war ended before the first production rifles were completed.

The German technicians involved in developing the StG 45(M) were taken to work in France at CEAM (Centre d'Etudes et d'Armement de Mulhouse). The StG 45(M) mechanism was modified by Ludwig Vorgrimler and Theodor Löffler at the Mulhouse facility between 1946 and 1949. Three versions were made, chambered in .30 Carbine, 7.92×33mm Kurz as well as the experimental 7.65×35mm French short cartridge developed by Cartoucherie de Valence in 1948. A 7.5×38mm cartridge using a partial aluminium bullet was abandoned in 1947. Löffler's design, designated the Carabine Mitrailleuse Modèle 1950, was retained for trials among 12 different prototypes designed by CEAM, MAC, and MAS. Engaged in the Indochina War and being the second NATO contributor, France canceled the adoption of these new weapons for financial reasons.

In 1950, Vorgrimler moved to Spain where he created the LV-50 rifle chambered for the Kurz cartridge and later, the proprietary 7.92×40mm CETME M53 round. At this point, the rifle was renamed the Modelo 2. The Modelo 2 drew the attention of the West German Border Guards (Bundesgrenzschutz), who sought to re-equip the newly formed national defense forces. Not willing to accept a cartridge outside of the NATO specification, the Germans asked CETME to develop a 7.62×51mm version of the rifle. The resulting CETME Model A was chambered for the 7.62×51mm CETME cartridge which was identical in chamber dimensions but had a reduced-power load compared to the 7.62mm NATO round. Further development of the rifle with input from H&K produced the CETME Model B which received several modifications, including the ability to fire from a closed bolt in both semi-automatic and automatic firing modes, a new perforated sheet metal handguard (the folding bipod had been the foregrip in previous models), improved ergonomics and a slightly longer barrel with a 22 mm rifle grenade launcher guide. In 1958, this rifle was accepted into service with the Spanish Army as the Modelo 58, using the 7.62×51mm CETME round.

In 1956, the Bundesgrenzschutz canceled their planned procurement of the CETME rifles, adopting the Belgian-made FN FAL (G1) instead. However, the newly formed West German Army (Bundeswehr) now showed interest and soon purchased a number of CETME rifles (7.62×51mm NATO chambering) for further testing. The CETME, known as the Automatisches Gewehr G3 according to German nomenclature, competed successfully against the Swiss SIG SG 510 (G2) and the American AR-10 (G4) to replace the previously favored G1 rifle. In January 1959, the Bundeswehr officially adopted the CETME proposal. The West German government wanted the G3 rifle to be produced under license in Germany; purchase of the G1 had previously fallen through over FN's refusal to grant such a license. In the case of the G3, the Dutch firm Nederlandse Wapen en Munitiefabriek (NWM) held production and sales rights to the CETME design outside of Spain. To acquire production rights, the West German government offered NWM contracts to supply the German Air Force (Luftwaffe) with 20 mm ammunition. Production of the G3 was then assigned to Rheinmetall and H&K. The latter company already had ties to CETME, and had worked to further optimize the CETME rifle for use with the full-power 7.62×51mm NATO cartridge (as opposed to the downloaded CETME variant).

In 1969, Rheinmetall gave up production rights to the G3 in exchange for H&K's promise not to bid on MG 3 production. Later in 1977, the West German government ceded ownership of G3 production and sales rights exclusively to H&K.
Initial production G3 rifles differed substantially from more recent models; early rifles featured closed-type mechanical flip-up sights (with two apertures), a lightweight folding bipod, a stamped sheet steel handguard, a wooden buttstock (in fixed stock models) or a telescopic metal stock. The weapon was modernized during its service life (among other minor modifications it received new sights, a different flash suppressor, and a synthetic handguard and shoulder stock), resulting in the most recent production models, the G3A3 (with a fixed polymer stock) and the G3A4 (telescoping metal stock). The rifle proved successful in the export market, being adopted by the armed forces of over 40 countries. The G3 was and in some cases continues to be produced under license in: France (MAS), Greece (Hellenic Arms Industry), Iran (Defense Industries Organization), Luxembourg (Luxemburg Defense Technologi), Mexico, Myanmar, Norway (Kongsberg Våpenfabrikk), Pakistan (Pakistan Ordnance Factories), Portugal (FBP), Saudi Arabia, Sweden (FFV), Thailand, Turkey (MKEK) and the United Kingdom (Royal Ordnance).

Design Detail.

The G3A3 (A4) is a selective-fire automatic weapon that employs a roller-delayed blowback operating system. The two-piece bolt assembly consists of a breech (bolt head) and bolt carrier. The bolt is held in battery by two sliding cylindrical rollers that engage locking recesses in the barrel extension (popularly called a "trunnion"; BATF calls this a "mounting block"). The breech is opened when both rollers are compressed inward against camming surfaces driven by the rearward pressure of the expanding gases upon the bolt head. As the rollers move inward, recoil energy is transferred to the locking piece and bolt carrier which begin to withdraw while the bolt head slowly moves rearward in relation to the bolt carrier. As the bolt carrier clears the rollers, pressure in the bore drops to a safe level, the bolt head is caught by the bolt carrier and moves to the rear as one unit, continuing the operating cycle. The bolt also features an anti-bounce mechanism that prevents the bolt from bouncing off the barrel's breech surface. The spring-powered claw extractor is also contained inside the bolt while the lever ejector is located inside the trigger housing (actuated by the recoiling bolt).

The rifle is hammer fired and has a trigger mechanism with a 3-position fire selector switch that is also the manual safety toggle that secures the weapon from accidentally discharging (fire selector in the “E” or “1” position – single fire mode ("Einzelfeuer"), “F” or “20” – automatic fire ("Feuerstoß"), “S” or “0” – weapon is safe ("Sicher"), trigger disabled mechanically). The weapon can be fitted with an optional 4-position safety/fire selector group illustrated with pictograms with an ambidextrous selector lever. The additional, fourth selector setting enables a 3-round burst mode of fire.

The firearm was equipped with iron sights that consist of a rotary rear drum and hooded front post. The rear sight, mechanically adjustable for both windage and elevation, has an open notch used to fire up to 100 m and three apertures used for: 200, 300 and 400 m.[5] The receiver housing has recesses that work with HK clamp adapters used to mount day or night optics.

The rifled barrel (contains 4 right-hand grooves with a 305 mm twist rate) terminates with a slotted flash suppressor which can also be used to attach a bayonet or serve as an adapter for launching rifle grenades. From the G3A3 the barrel had polygonal rifling.

The barrel chamber is fluted, which assists in the initial extraction of a spent cartridge casing (since the breech is opened under very high barrel pressure).

The G3A3 (A4) uses either steel (260 g) or aluminium (140 g) double-stacked straight box magazines, or a 50 round drum magazine. Original H&K drums are rare and command high prices, a reproduction is available at much less cost from Allied Armament. H&K developed a prototype plastic disposable magazine in the early 1960s, but it was not adopted as aluminum magazines were just as light and proved more durable, as well as easier to produce.

Standard accessories supplied with the rifle include: a detachable bipod (not included with rifles that have a perforated plastic handguard), sling, cleaning kit and a speed-loading device. Several types of bayonet are available for the G3, but with few exceptions they require an adapter to be inserted into the end of the cocking tube. The most common type features a 6¾ inch spear-point blade nearly identical with the M7 bayonet, but with a different grip because of its mounting above the barrel. The weapon can also mount a 40 mm HK79 under-barrel grenade launcher, blank firing adapter a straight blowback bolt (called a “PT” bolt, lacks rollers) used for firing 7.62×51mm ammunition with plastic bullets, a conversion kit used for training with .22 LR ammunition and a sound suppressor (that uses standard ammunition).

The G3 is a modular weapon system. Its butt-stock, fore-stock and pistol-grip/fire-control assembly may be changed at will in a variety of configurations (listed below). For example: by simply removing push pins the fixed butt-stock can be removed and replaced with a telescoping butt-stock.