RPK-47

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When faced with the need for a light machine gun, the Soviets naturally turned to preexisting designs. And what better foundation is there than the Ak-47?

RPK Specifications
The RPK (Ruchnoi Pulement Kalashnikova) is very similar in design, form, and function to the AKM/AK-47. It fires the same 7.62x39mm ammunition, and the AKM and RPK share many parts. The RPK and AKM sport identical pistol grips, rear spring guide rods (though it has a different forward guide rod), and are capable of running the same magazines.

What is different is a direct result of the desire to increase the effective range of the rifle, increase resilience and durability, and enhance the sustained fire capability of the platform by increasing heat capacity and reducing bore erosion. The RPK has a longer, heavier, chrome-lined barrel, and a folding bipod, in addition to a beefed up 1.5mm thick stamped receiver (compared to the 1mm thick AK-47 receiver). The receiver cover is also thicker than that found on the AK-47. Even the trunion securing the barrel to the receiver is made stronger by the addition of slightly wider ribbing than is utilized on the AKM. It also has a modified, slotted, muzzle break.

Larger magazines are used with the RPK, adding the sustained fire capability of the rifle; 40-round box magazines and 75-round drum magazines, both of which are compatible with AK-47 and it's variants, were developed for use with the RPK. The RPK has a cyclic rate of around 650 rounds per minute, and an effective range approaching 700 yards. The RPK does have some serious drawbacks as a light machine gun: The barrel is fixed, and not able to be swapped in the field. Additionally, since the rifle fires from a closed bolt, excess heat build up can lead to rounds "cooking off" from the heat of the bolt. Given these drawbacks, the rifle must be fired in short bursts to avoid damaging the barrel or cooking of rounds.

Variants
Like the AK-47, there are many variants of the RPK-47. The most common is probably the RPKS, which was issued to the airborne infantry. It had a wooden side-folding stock to allow it to be more easily packed by air-drop units. Incorporating the folding stock required extensive modification to the rear trunnion, which was riveted to both walls of the receiver. A socket was integrated into the trunnion which allowed the stock to connect with a pivot pin. A latch was also built into a cut-out on the side of the trunnion which would engage a catch on the stock and lock it into the open position.

Other variants include the N-model, which was the night-fighting version of the RPK, designated the RPKN or RPK-74N. On this model, night vision and infrared scopes, usually models NSP-3, NSPU or NSPUM, were mounted on a left-side rail which was mounted on the receiver.

RPK-74
When the AK-74 was introduced in 1974, the new modified RPK was also introduced. Both rifles are chambered in 5.45x39mm. The RPK-74, like the AK-74, is a modernized version of the 47 model. The RPK-74 sports many of the same improvements as the AKM, but with a few additional changes. The rear trunnion was further reinforced, and the barrel was threaded to use either a flash suppressor or a blank-firing adapter. A newly-designed front sight base was also used on the RPK-74. The RPK-74 is still in use today by the former Soviet Union states, as well as much of Eastern Europe including Poland, Romania, Bulgaria, and Yugoslavia. Other communist bloc nations such as North Korea and China also utilize versions of the RPK-74.

Growth into the Export and Civilian Market
As demand for the rifle grew, another model of the RPK was developed, the RPK-74M. This new model has all polymer furniture as well as a standard side rail. Export models designated the RPK-201 were chambered in 5.56 NATO along with the RPKM model which was chambered in 7.62x39. Semiautomatic models known as the Veper and Veper 2 were created for the burgeoning US civilian market and are available in .223, 7.62x39, and .308 Winchester.