The RPK (Ruchnoy Pulemyot Kalashnikova, Russian: Ручной пулемёт Калашникова or "Kalashnikov hand-held machine gun") is a 7.62x39mm light machine gun of Soviet design, developed by Mikhail Kalashnikov in the late 1950s, parallel with the AKM assault rifle. It was created as part of a program designed to standardize the small arms inventory of the Red Army, where it replaced the 7.62x39mm RPD light machine gun. The RPK continues to be used by the armed forces of countries of the former Soviet Union and certain African and Asian nations. The RPK was also manufactured in Bulgaria and Romania.
A variant of the RPK equipped with a side-folding wooden stock and intended primarily for use with air assault infantry (in the former Soviet Union the RPK was issued mainly to motorised units). Changes to the design of the RPKS are limited only to the shoulder stock mounting, at the rear of the receiver. It uses a trunnion riveted to both receiver walls that has a socket and tang, allowing the stock to hinge on a pivot pin. The trunnion has a cut-out on the right side designed to engage the stock catch and lock it in place when folded. The wooden stock is mounted in a pivoting hull, which contains a catch that secures the buttstock in the extended position. The rear sling loop was moved from the left side of the stock body to the right side of the stock frame.
Additionally, the RPK-74 has a modified return mechanism compared to the AK-74, which uses a new type of metal spring guide rod and recoil spring. The rear sight assembly, forward handguard and receiver dust cover were all retained from the RPK.The rear stock trunnion was strengthened and the magazine well was reinforced with steel inserts.
The RPK-74 feeds from a 45-round steel or polymer magazine, interchangeable with magazines from the AK-74, and is designed to be charged from stripper clips.
Standard equipment includes: eight magazines, six stripper clips (15 rounds per clip), a speedloader guide, cleaning rod, cleaning kit, sling, oil bottle and two magazine pouches. Some variants do not come with the cleaning kit option.
It is in widespread use by member states of the former Soviet Union, as well as Bulgaria and the Polish Armed Forces (limited).
The RPKS-74 is the paratrooper model of the RPK-74, equipped with a wooden folding stock from the RPKS.
The RPK family of light machine guns is also available in a night fighting configuration. The weapons are then designated RPKN, RPKSN, RPK-74N, RPKS-74N and equipped with a side rail mounting on the left side of the receiver which is used to attach a NSP-3, NSPU or NSPUM night vision sight.
An improved variant known as the RPK-74M was developed that includes a polymer foregrip, pistol grip and side-folding stock as well as a side rail for mounting optics. An export variant chambered in 5.56x45mm NATO was also introduced, designated the RPK-201. Also for export is the RPKM chambered in 7.62x39mm; it uses the same polymer furniture as the RPK-74M variant. A series of semi-automatic rifles based on the RPK receiver are manufactured by the "Molot" factory in Russia, these are known as the Vepr and Vepr 2. They are offered in several chamberings, including: .223 Remington, 7.62x39mm and .308 Winchester. They are intended mainly for the civilian market.