RPK 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 . 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 . Design details . The RPK functions identically to the AK - 47 . It also uses the same 7 . 62x39mm ammunition . It has a similar design layout to the AKM and AK - 47 series of rifles , with modifications to increase the RPK ' s effective range and accuracy , enhance its sustained fire capability , and strengthened receiver . Features . Most notably , the RPK has a heavier and longer barrel than an AKM . This allows the RPK to fire for extended periods of time without major loss in accuracy is due to the barrel heating up . The chrome - lined barrel is permanently fixed to the receiver , and cannot be replaced in the field . It is fitted with a new front sight base , gas block ( lacks the bayonet lug ) and an under - barrel cleaning rod guide . The barrel also features a folding bipod , mounted near the muzzle , and a front sight base with a lug that limits the bipod ' s rotation around the axis of barrel . The barrel ' s muzzle is threaded , enabling the use of muzzle devices such as flash hiders , compensators , and blank - firing adapters . When a muzzle device is not being used , the threads on the muzzle can be covered by a thread protector . The barrel is pinned to the receiver in a modified trunnion , reinforced by ribbing , and is slightly wider than the trunnion used on standard AKM type rifles . Symmetrical bulges on both sides of the front trunnion ensure proper fit inside the receiver . The RPK ' s receiver cover is stamped from a smooth 1 . 5 mm ( 0 . 1 in ) sheet of steel ( compared to the 1 mm sheet metal receiver cover used on standard AKM rifles ) . Interchangeability of parts between the RPK and AKM is moderate . The RPK uses a modified AKM recoil spring assembly . It consists of a rear spring guide rod from the AKM , and a new forward flat guide rod and coil spring . The RPK features a thick laminated wood foregrip , and a fixed laminated wood " club - foot " buttstock , similar to the stock used on the RPD , which is designed to allow the user to fire from the prone position more comfortably . The RPK uses a standard AKM pistol grip . The weapon can use standard AKM detachable box magazines , but is most commonly used with a 40 round capacity magazine , or a 75 round drum magazine . Sights . The weapon ' s rear sight leaf is elevation adjustable , and graduated for ranges of 100 to 1 , 000 meters , in 100 m increments . The rear sight leaf also features a windage adjustment knob , unique to the RPK series of rifles . Accessories . Supplied with the RPK are : spare magazines , a cleaning rod , cleaning kit ( stored in a hollowed compartment in the butt stock ) , a sling , oil bottle and magazine pouches ( a single - pocket pouch for a drum magazine or a 4 - pocket pouch for box magazines ) . An RPK with a side - folding wooden stock was intended primarily for the air assault infantry . Changes to the design of the RPKS are limited only to the shoulder stock mounting , at the rear of the receiver . It uses a grunion riveted to both receiver walls that has a socket and tang , allowing the stock to hinge on a pivot pin . The grunion 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 butt stock 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 . Introduced in 1974 together with the AK - 74 and chambered for the new 5 . 45x39mm high - velocity cartridge . The RPK - 74 derives from the AK - 74 rifle , with modifications that mirror those made to the AKM to create the RPK . The RPK - 74 also uses a longer and heavier chrome - plated barrel , which has a new gas block with a gas channel at a 90° angle to the bore axis , and a ring for the cleaning rod . The RPK - 74 was also equipped with a folding bipod and a different front sight tower . The muzzle is threaded for a blank - firing device . The rear stock grunion was strengthened and the magazine well was reinforced with steel inserts . 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 hand guard and receiver dust cover were all retained from the RPK . The RPK - 74 feeds from a 45 - round steel or polymer box magazine , interchangeable with magazines from the AK - 74 , and is designed to be charged from stripper clips . Drum magazines similar to those used on the previous RPK models were tested during the development phase of the RPK - 74 , but were discontinued in favor of the 45 - round box magazine . Standard equipment includes : eight magazines , six stripper clips ( 15 rounds per clip ) , a speed loader 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 . RPKS - 74 The RPKS - 74 is the paratrooper model of the RPK - 74 , equipped with a wooden folding stock from the RPKS . Night variants The RPK family of light machine guns is also available in a night fighting configuration . These weapons are designated RPKN , RPKSN , RPK - 74N , and RPKS - 74N . They have a side rail mounting on the left side of the receiver that accepts a NSP - 3 , NSPU , or NSPUM night vision sight .