Heckler & Koch G3 2.96

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).[5]
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.[5]
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.[6] 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).[5]
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.



Variants


Apart from the G3A3 and G3A4 HK also built: the G3A3ZF (essentially a G3A3 with a Hensoldt 4×24 optical sight), the accurized G3SG/1 rifle (hand-selected G3A3s, equipped with an improved trigger, Zeiss telescopic sight with a variable 1.5–6× magnification and a cheek riser) and the G3K carbine which uses an HK33 handguard and a short barrel (reduced in length to the base of the front sight post), that is too short for use with a bayonet or rifle grenades.[5]
The G3 served as a basis for many other weapons, among them: the PSG1 and MSG90 precision rifles, the HK11 and HK21 family of light machine guns, a semi-automatic version known as the HK91, a "sporterized" model called the SR9 (designed for the civilian market in countries where the HK91 would not qualify, primarily the US after the 1989 importation restrictions) and the MC51 carbine, produced by the UK firm FR Ordnance International Ltd. for special forces. The MC51 weighs 3.1 kg (6.8 lb), has a folded overall length of 625 mm (24.6 in), a barrel length of only 230 mm (9.1 in), which produces a muzzle velocity of approx. 690 m/s (2,263.8 ft/s) and a muzzle energy of 2215 J. The MC51 was allegedly manufactured for the British SAS and SBS, who required a compact but powerful weapon, for situations in which the stopping power and armor piercing capabilities of 9×19mm Parabellum round were inadequate. Only 50 weapons were produced, and all were reportedly shipped to the UK special forces. Most of them were soon replaced by the Heckler & Koch HK53 carbine. Another UK-based company called Imperial Defence Services Ltd. absorbed FR Ordnance and continues to market the MC51 standard variant.




G3: Original model based on the CETME Modelo B.
G3A1: G3 with a single position, collapsible stock. This design was chosen after earlier experimentation with a ventrally-folding stock. Excessive recoil caused the latter to be dropped from consideration.
G3A2: G3 with new rotating drum rear sight.
G3A3: The most well known version. Drum sights, a fixed plastic buttstock, and a plastic handguard that does not contact the barrel. The handguard came in a slim, ventilated version and a wide version. The latter allows for the attachment of a bipod.
G3A3A1: This is a version of the G3A3 with an ambidextrous trigger group and brass deflector. This is an official German Army designation, not an HK factory one.
G3A4: The G3A4 uses drum sights and a single position, collapsible stock. This rifle could also be issued with a scope with the nomenclature G3A4ZF. The ZF stands for Zielfernrohr or "Telescope".
G3A4A1: This is a variant of the G3A4 with an ambidextrous trigger group and brass deflector. This is an official German Army designation, not an HK factory one.
G3KA4: Smallest of the line, it is a Karabiner, or carbine version of the G3. It features drum sights, a retractable stock, and a 315 mm (12.4 in) barrel.
G3KA4A1: Variant of the G3KA4 with an ambidextrous trigger group and brass deflector. This is an official German Army designation, not an HK factory one.
G3A5: HK assigned model number for the HK-made Danish version of the G3A3. It differs in that it has a silent bolt-closure device. In Danish service it is known as the Gv M/66. The Gv M/66 was originally intended for use with optics as a designated marksman rifle, while the rest of the squad were issued M1 Garands.
G3A6: HK assigned model number for the Iranian-made version of the G3A3.
G3A7: HK assigned model number for the Turkish-made version of the G3A3.
HSG1: HK assigned model number for the Luxembourg- made version of G3A3.