Heckler And Koch G-3

Heckler And Koch G-3

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. The receiver housing has recesses that work with HK clamp adapters used to mount day or night optics.



Specifications

Cartridge    7.62×51mm NATO
Action    Roller-delayed blowback
Rate of fire    500–600 rounds/min
Muzzle velocity    800 m/s (2,625 ft/s)
Effective range    500 metres (550 yd), 100–400 m sight adjustments
Feed system    20-round detachable box and 50-round drum magazine
Sights    Rear: rotary diopter; front: hooded post[/QUOTE]