AK-74
The AK-74 is an assault rifle designed by small arms designer Mikhail Kalashnikov in 1974 as a successor to the AKM. It is chambered for the 5.45×39mm cartridge, which replaced the 7.62×39mm cartridge of Kalashnikov's earlier automatic weapons for the Soviet Armed Forces.
The rifle first saw service with Soviet forces in the Soviet–Afghan War from 1979. The head of the Afghan bureau of the Inter-Services Intelligence, the intelligence agency of Pakistan, claimed that the American Central Intelligence Agency paid $5,000 for the first AK-74 captured by the Afghan mujahideen during the war.
, most countries of the former Soviet Union use the rifle. Licensed copies were produced in Bulgaria, and in the former East Germany.
Design details
The AK-74 was designed by А. D. Kryakushin's group under the design supervision of Mikhail Kalashnikov. It is an adaptation of the 7.62×39mm AKM assault rifle and features several important design improvements. These improvements were primarily the result of converting the rifle to the intermediate-calibre high velocity 5.45×39mm cartridge. In fact, some early models are reported to have been converted AKMs, re-barreled to 5.45×39mm. Compared with the preceding AKM, the AK-74 has better effective firing range, accuracy, and reliability. About 50% of the parts in the AK-74 and AKM are the same.Operating mechanism
The rifle's operation during firing and reloading is identical to that of the AKM. After ignition of the cartridge primer and propellant, rapidly expanding propellant gases are diverted into the gas cylinder above the barrel through a vent near the muzzle. The build-up of gases inside the gas cylinder drives the long-stroke piston and bolt carrier rearward and a cam guide machined into the underside of the bolt carrier along with an ejector spur on the bolt carrier rail guide, rotates the bolt approximately 35° and unlocks it from the barrel extension via a camming pin on the bolt. The moving assembly has about of free travel which creates a delay between the initial recoil impulse of the piston and the bolt unlocking sequence, allowing gas pressures to drop to a safe level before the seal between the chamber and the bolt is broken. Like previous Kalashnikov-pattern rifles, the AK-74 does not have a gas valve; excess gases are ventilated through a series of radial ports in the gas cylinder. Since the Kalashnikov operating system offers no primary extraction upon bolt rotation, the 5.45×39mm AK-74 bolt has a larger extractor claw than the 7.62×39mm AKM for increased extraction reliability. Other minor modifications were made to the bolt and carrier assembly.Barrel
The rifle received a new barrel with a chrome-lined bore and 4 right-hand grooves at a 200 mm or 37 calibers rifling twist rate. The front sight base and gas block were redesigned. The gas block contains a gas channel that is installed at a 90° angle in relation to the bore axis to reduce bullet shear at the port hole. A pair of support brackets are cast into the gas block assembly and are used to attach a BG-15c or GP-25 underslung 40 mm grenade launcher. Like the AK-47 and AKM, the muzzle is threaded for the installation of various muzzle devices such as the standard muzzle brake or a blank-firing adaptor, while a spring-loaded detent pin held in the front sight post prevents them from unscrewing while firing. However the muzzle threads have been relocated to the front sight base for both easier and more economic replacement in case of thread damage. The distinctive standard-issue muzzle brake features a large expansion chamber, two symmetrical vertical cuts at the forward end of the brake and three non symmetrical positioned vent holes to counteract muzzle rise and climb as well as lateral shift to the right much like the AKM's offset muzzle brake. A flat plate near the end of the brake produces a forward thrust when emerging exhaust gases strike its surface, greatly reducing recoil. The muzzle brake prevents backblast from reaching the firer, although it is reported to be harsh on bystanders as the muzzle gases are dispersed to the sides. The standard-issue AK-74 muzzle brake has been subtly revised several times since the 1970s.Sights
Iron sights
The AK-74 uses an adjustable notched rear tangent iron sight calibrated in increments from. The front sight is a post adjustable for elevation in the field. Horizontal adjustment requires a special drift tool and is done by the armoury before issue or if the need arises by an armourer after issue. The sight line elements are approximately over the bore axis. The "point-blank range" battle zero setting "П" standing for постоянная the 5.45×39mm AK-74 rear tangent sight element corresponds to a zero, compared with the zero for 7.62×39mm AKs. For the AK-74 combined with the 7N6 or 7N10 service cartridges the 400 m battle zero setting point-blank range limits the apparent "bullet rise" within approximately under the line of sight. At the corresponding maximum point-blank range the bullet will have dropped to approximately relative to the line of sight. Soldiers are instructed to fire at any target within this range by simply placing the sights on the center of mass of the enemy target. Any errors in range estimation are tactically irrelevant, as a well-aimed shot will hit the torso of the enemy soldier.Optical sights
While most Russian and CIS armed forces use the AK-74 in its basic configuration with iron sights, many magnified and non-magnified optical sights are available for designated marksmen and other special purpose troops in their respective militaries.For the 5.45×39mm AK-74, the East German Zeiss ZFK 4×25, USP-1 , Belorussian BelOMO PO 3.5×21P, PO 4×24P and the 1P78 Kashtan dedicated side rail mounted optical sights were developed. These optical sights are primarily designed for rapid target acquisition and first round hits out to 400 m, but by various means these optical sights also offer bullet drop compensation for aiming at more distant targets. The BDC feature compensates for the effect of gravity on the bullet at given distances in flat fire scenarios. The feature must be tuned for the particular ballistic trajectory of a particular combination of gun and cartridge at a predefined muzzle velocity and air density. Since the usage of standardized ammunition is an important prerequisite to match the BDC feature to the external ballistic behaviour of the employed projectiles, these military optical sights are intended to assist with field shooting at varying medium to longer ranges rather than precise long range shots.
The standard Russian side rail mounted optical sight was the 4×26 1P29 Universal sight for small arms. It was copied from and hence similar to the British SUIT. When mounted the 1P29 sight is positioned centered above the receiver at a height that allows the use of the iron sights. It weighs 0.8 kg, offers 4× magnification with a field of view of 8° and 35 mm eye relief. The 1P29 is issued with a canvas pouch, a lens cleaning cloth, combination tool, two rubber eyecups, two eyecup clamps and three different bullet drop compensation cams for the AK-74/AN-94, RPK-74 and PK machine gun. The 1P29 is intended for quickly engaging point and area targets at various ranges and is zeroed for both windage and elevation at. On the right side of the field of view a stadiametric rangefinder is incorporated that can be used to determine the distance from a tall object from. The reticle is an inverted aiming post in the top half of the field of view and is tritium-illuminated for low-light condition aiming.
The current Russian standard side rail mounted optical sight for the AK-74M is the 2.8×17 1P78 Kashtan, an aiming optic similar to the American ACOG. When mounted the 1P78 sight is positioned centered above the receiver. It weighs 0.5 kg, offers 2.8× magnification with a field of view of 13° and 32 mm eye relief. The 1P78 comes in several versions for the AK-74, RPK-74, AKM and RPK. The 1P78 is intended for quickly engaging point and area targets at various ranges and is zeroed for both windage and elevation at. A stadiametric rangefinder is incorporated that can be used to determine the distance for a soldier sized target from. The reticle consist of a main 400 m "chevron", a holdover dot and smaller additional holdover chevrons for and and is tritium-illuminated for low-light condition aiming.
New features
The AK-74 was equipped with a new buttstock, handguard and gas cylinder. The stock has a shoulder pad different from that on the AKM, which is rubber and serrated for improved seating against the shooter. In addition, there are lightening cuts on each side of the buttstock. The buttstock, lower handguard and upper heatguard were first manufactured from laminated wood, this later changed to a synthetic fiberglass-reinforced polyamide 6 colored with "kaprozol brown 4K" disperse dye, the color of which is usually referred to as "Russian Plum". The introduction of the new material was slow and impeded by very stringent hardness requirements of the military which no Western polymer furniture was able to satisfy as of 1980.The AK-74 gas tube has a spring washer attached to its rear end designed to retain the gas tube more securely. The lower handguard is fitted with a leaf spring that reduces play in the rifle's lateral axis by keeping the wood tensioned between the receiver and the handguard retainer. The receiver remains nearly identical to that of the AKM; it is a U-shaped thick sheet steel pressing supported extensively by pins and rivets. The internal guide rails on which the bolt carrier travels are stamped and spot welded to the inside of the receiver housing. Minor changes were made to the front barrel and rear stock trunnions as well as the magazine well. All external metal surfaces are coated with a glossy black enamel paint.