In the second half of the forties, the Soviet army mastered several types of small arms for the intermediate cartridge 7, 62x39 mm. With a difference of several years, the RPD light machine gun, the SKS carbine and the AK assault rifle were adopted. This weapon made it possible to significantly increase the firepower of motorized rifle subunits and thereby increase their combat potential. Nevertheless, the development of small arms was continued, as a result of which several new models appeared. The Degtyarev light machine gun (RPD) was replaced by the Kalashnikov light machine gun (RPK).
The development and use of weapons under one cartridge made it possible to significantly simplify the supply of ammunition to the troops. In the early fifties, there was a proposal to continue the unification of existing systems, this time by creating families of weapons. In 1953, the Main Artillery Directorate developed tactical and technical requirements for a new family of small arms chambered for 7, 62x39 mm. The military wanted to get a complex consisting of a new machine gun and a light machine gun. Both samples were supposed to have the most similar design using common ideas and details. The technical assignment implied that the new "lightweight" machine gun in the near future will replace the existing AK in the troops, and the machine gun unified with it will become a replacement for the existing RPD.
Several leading gunsmiths took part in the competition for the creation of a new shooting complex. V. V. Degtyarev, G. S. Garanin, G. A. Korobov, A. S. Konstantinov and M. T. Kalashnikov. The latter submitted to the competition two types of weapons, which were subsequently adopted into service under the names AKM and PKK. The first tests of the proposed weapon took place in 1956.
Tests and modifications of the proposed assault rifles and machine guns continued until 1959. The result of the first stage of the competition was the victory of the Kalashnikov assault rifle. In 1959, the AKM assault rifle was adopted by the Soviet army, which to a certain extent predetermined the choice of a new light machine gun. The Kalashnikov machine gun itself was put into service two years later. During this time, the designer improved its design and, while maintaining the required degree of unification, brought the characteristics to the required level.
At the request of the customer, the new light machine gun was supposed to repeat as much as possible the design of the machine gun, which was being developed simultaneously with it. As a result, the RPK designed by M. T. Kalashnikov's many features resembled an AKM assault rifle. Naturally, the design of the machine gun provided for some differences associated with its intended use.
The RPK machine gun was built on the basis of gas automatics with a long piston stroke. This scheme has already been worked out in the AK project and passed to AKM and RPK without significant changes. In terms of the general layout of components and assemblies, the new machine gun also did not differ from the existing and promising machine guns.
The main part of the RPK machine gun was a rectangular receiver. For access to the indoor units, a removable cover with a latch at the rear was provided. In front of the receiver, a barrel and a gas tube were attached. The experience of using RPD and other similar weapons showed that a new light machine gun can do without a replaceable barrel. The fact is that a heavy barrel with relatively thick walls did not have time to overheat even during the use of all wearable ammunition. To increase the firepower in comparison with the basic machine gun, the RPK machine gun received a barrel length of 590 mm (415 mm for the AKM).
A gas tube with a piston was located directly above the barrel. The middle part of the receiver was reserved for the shutter assemblies and magazine mounts, the rear - for the firing mechanism. An updated receiver has become a characteristic feature of the RPK machine gun. It almost did not differ from the corresponding part of the machine gun, but had a reinforced structure. The box and lid were stamped from steel sheet, which simplified production in comparison with milled units of AK automatic machines.
All automation parts were borrowed from the basic machine without changes. The main element of the gas engine was a piston rigidly connected to the bolt carrier. The barrel was locked before firing by turning the bolt. When moving forward, during the chambering of the cartridge into the chamber, the bolt interacted with the figured groove on the bolt carrier and rotated around its axis. In the extreme forward position, it was fixed with two lugs that fit into the corresponding grooves of the receiver liner. The bolt carrier with its rear part was in contact with the return spring located directly under the receiver cover. To simplify the design, the bolt handle was part of the bolt carrier.
Requirements for the resource of the barrel and various automation parts led to the need to use chrome plating. The coating received the barrel bore, the inner surface of the chamber, the piston and the bolt carrier. Thus, protection was obtained by parts that are in direct contact with propellant gases that can cause corrosion and destruction.
In the rear of the receiver there was a hammer-type firing mechanism. In order to preserve the maximum possible number of common parts, the RPK machine gun received a trigger with the ability to fire single and in automatic mode. The flag of the fuse-translator of fire was located on the right surface of the receiver. In the raised position, the flag blocked the trigger and other parts of the trigger, and also did not allow the bolt carrier to move. Due to the continuity of the design, the shot was fired from the front sear, with the cartridge sent and the barrel locked. Despite the concerns, the thick barrel and shooting in mostly short bursts did not allow spontaneous firing due to overheating of the sleeve.
For ammunition supply, the RPK machine gun had to use several types of stores. The unification of the design with the AKM assault rifle made it possible to use the existing sector magazines for 30 rounds, but the need to increase the firepower of the weapon led to the emergence of new systems. Kalashnikov light machine guns were equipped with two types of magazines. The first is a two-row sector 40 rounds, which was a direct development of the automatic magazine. The second magazine had a drum design and held 75 rounds.
Inside the body of the drum store, a spiral guide was provided, along which the cartridges were located. In addition, when equipping such a store, the machine gunner had to cock the spring cartridge feed mechanism. Under the action of a cocked spring, a special pusher led the cartridges along the guide and pushed them to the neck of the store. A characteristic feature of the drum mechanism was certain difficulties with its equipment. This process was more complicated and took longer than working with a sector store.
For aiming, the shooter had to use a front sight mounted above the muzzle of the barrel, and an open sight on the front of the receiver. The sight had a scale with divisions from 1 to 10, which made it possible to fire at a distance of up to 1000 m. It also provided for the possibility of lateral amendments. By the time the new machine gun was adopted, the production of a device for firing at night was mastered. It consisted of an additional rear sight and a front sight with self-luminous dots. These parts were installed on top of the basic sighting devices, and, if necessary, could be folded back, allowing the use of the existing rear sight and front sight.
The ease of operation of the RPK machine gun was provided by the presence of several wooden and metal parts. To hold the weapon, a wooden forend and a pistol grip should be used. In addition, a wooden butt was attached to the receiver. The form of the latter was partially borrowed from the RPD machine gun available in the troops. When firing prone or with an emphasis on an object with a bipod, the machine gunner could hold the weapon by the thin neck of the butt with his free hand, which had a positive effect on the accuracy and accuracy of fire. Behind the front sight mounts on the barrel were the bipod mounts. In the transport position, they were folded and placed along the trunk. In the unfolded position, the bipod was held by a special spring.
Light machine gun designed by M. T. Kalashnikovs turned out to be noticeably larger and heavier than the unified assault rifle. The total length of the weapon reached 1040 mm. The weight of the weapon without a magazine was 4.8 kg. For comparison, the AKM assault rifle without a bayonet-knife had a length of 880 mm and weighed (with an empty metal magazine) 3.1 kg. A metal magazine for 40 rounds weighed about 200 g. The weight of a drum magazine reached 900 g. It should be noted that the RPK with ammunition was noticeably lighter than its predecessor. The RPK with a loaded drum magazine weighed about 6, 8-7 kg, while the RPD with a tape without cartridges pulled 7, 4 kg. All this increased the mobility of the soldier on the battlefield, although it could affect some of the combat characteristics of the weapon.
The worked out automation, borrowed from the existing model, made it possible to achieve a rate of fire at the level of 600 rounds per minute. The practical rate of fire was less and depended on the operating mode of the trigger. When firing single shots per minute, it was possible to make no more than 40-50 shots, with automatic fire - up to 150.
With the help of a barrel of increased length, it was possible to bring the muzzle velocity of the bullet to 745 m / s. The aiming range was 1000 m. The effective firing range at ground targets was less than 800 m. From a distance of 500 m it was possible to conduct effective fire at flying targets. Thus, most of the combat qualities of the RPK machine gun remained at the level of the RPD troops. At the same time, there was a significant gain in weight and unification of the design with a machine gun. The requirements for a normal battle of RPK and RPD machine guns were the same. When firing from 100 m, at least 6 out of 8 bullets had to hit a circle with a diameter of 20 cm. The deviation of the midpoint of impact from the aiming point could not exceed 5 cm.
RPKS machine gun
Simultaneously with the RPK light machine gun, its folding version of the RPKS, intended for the airborne troops, was being developed. Its only difference from the basic design was the folding stock. To reduce the length of the weapon to 820 mm, the butt was folded to the left and fixed in this position. The use of the hinge and some related parts led to an increase in the weight of the weapon by about 300 g.
Later, a "night" modification of the machine gun appeared. The RPKN product differed from the basic version by the presence of a mount on the left side of the receiver, on which any suitable night sight could be installed. The sights NSP-2, NSP-3, NSPU and NSPUM could be used with the RPK machine gun. With the development of sighting devices, the target detection range increased, although even the most advanced night sights did not allow firing at the maximum possible distance.
The Kalashnikov light machine gun was adopted by the Soviet army in 1961. Serial production of new weapons was launched at the Molot plant (Vyatskiye Polyany). Machine guns were massively supplied to the troops, where they gradually replaced the existing RPDs. The light machine guns of the new model were a means of strengthening motorized rifle squads and, from the point of view of a tactical niche, were a direct replacement for the existing RPDs. It took several years to completely replace the outdated weapon.
Having provided its own army with new weapons, the defense industry began to export them. Approximately in the mid-sixties, the first batches of RPK machine guns were sent to foreign customers. Soviet-made machine guns were delivered to more than two dozen friendly countries. In many countries, such weapons are still used today and are the main light machine gun in the army.
Some foreign countries have mastered the licensed production of Soviet machine guns, and also developed their own weapons based on the purchased PKK. Thus, in Romania, the Puşcă Mitralieră model 1964 machine gun was produced, and Yugoslavia since the early seventies has been collecting and using the Zastava M72 products. Yugoslav specialists further modernized their development and created the M72B1 machine gun. In 1978, the Yugoslavs sold the license for the production of the M72 by Iraq. There, these weapons were produced in several versions. There is information about our own modernization projects.
Iraqi military with PKK machine guns. Photo En.wikipedia.org
Back in the sixties, Vietnam became the most important customer of the RPK machine guns. The Soviet Union supplied at least several thousand units of such weapons to the friendly troops that took part in the war. The establishment of relations between the USSR and many developing countries in Asia and Africa, among other things, led to the use of PKK machine guns in many armed conflicts on several continents. This weapon was actively used in Vietnam, Afghanistan, in all Yugoslav wars, as well as in many other conflicts, up to the civil war in Syria.
In the early seventies, Soviet gunsmiths developed a new intermediate cartridge 5, 45x39 mm. The military decided to make it the main ammunition for small arms, for which several new assault rifles and machine guns were developed. In 1974, the AK-74 assault rifle and the RPK-74 light machine gun designed by M. T. Kalashnikovs using a new cartridge. The transfer of the army to a new ammunition affected the further fate of the existing weapons. Obsolete AK assault rifles and RPK machine guns were gradually replaced with new weapons and sent for storage, disposal or export. Nevertheless, the replacement of old weapons continued for a long time, which affected the terms of its operation.
The Kalashnikov RPK light machine gun became an important milestone in the history of the development of modern domestic small arms. With the help of this machine gun, a serious issue of unification of various shooting systems was resolved. Through the use of general ideas and some unified units, the authors of the project managed to significantly simplify and reduce the cost of weapons production while maintaining the characteristics at the level of the existing RPD. This was the main advantage of the new machine gun.
Posters for the operation of RPK machine guns. Photo Russianguns.ru
However, the RPK machine gun was not without its drawbacks. First of all, it is necessary to note the decrease in ammunition ready for use. The RPD machine gun was equipped with a belt for 100 rounds. The kit for the RPK had a sector magazine for 40 and a drum magazine for 75 rounds. Thus, without replacing the magazine, the shooter could make at least 25 shots less. At the same time, however, it took less time to replace the magazine than to refuel a new belt.
Another drawback of the RPK machine gun was associated with the used automation. Most machine guns fire from an open bolt: before firing, the bolt is in the rearmost position, which, among other things, improves barrel cooling. In the case of the RPK, the chambering of the cartridge into the chamber occurred before the trigger was pressed, and not after, as is the case with other machine guns. This feature of the weapon, despite the heavy barrel, limited the intensity of fire and did not allow long bursts of fire.
The PKK machine guns were actively used by the Soviet army for several decades. Some armies still use these weapons. Despite its considerable age, this weapon still suits the military of many countries. One can argue for a long time about the pros and cons of the Kalashnikov light machine gun, but the half-century history of operation speaks for itself.
