Take an AK-47, give it a 75-round magazine then make it even more robust as to allow for long periods of full auto firing. What you would get might look like the RPK light machine gun and in a world where assault rifles are princes and the AK-47 is an aging king, the RPK is a god on the battlefield.
Machine guns were the deciding factor on modern battlefields ever since 1914. During World War One the US Army introduced the Browning M1918 BAR automatic rifle, a 16-pound select fire gun that spat 30.06 ammo out at 650-round per minute until its 20-round magazine ran out. These smaller, one-man machine guns could be issued
down to the squad level to provide a huge increase in firepower. By World War II, the concept of a squad automatic weapon was widely spread and the Soviets wanted one.
Their first model, Vasily Degtyaryov’s RPD, came in at 16.31-pounds empty and brought a 100-round belt of 7.62x39mm ammo into the battlefield in 1945. While the RPD was a nice gun, it was heavy and used a milled receiver, which made production slow. In 1947 the Soviets went with the stamped receiver AK-47 and soon enough they were brainstorming about how to replace the RPD with a lighter and more AK-ish weapon.
This led to the RPK
Mikhail Kalashnikov, generally credited with the invention of the AK47/AKM assault rifle (even though he had a good bit of help from some German guests of the Motherland), was the primary mind behind the RPK. The name of the gun itself, Ruchnoy Pulemyot Kalashnikova, means literally ‘The Handheld Machinegun of Kalashnikov’. Using the same gas operated action with a rotating bolt and receiver bent from a stamped sheet, it was essentially just an upgrade to his older design. Whereas most standard Soviet AKs had a 1-mil thick receiver wall, the RPK’s was stretched to 1.6-mil thick. The thickness helped to reduce fatigue, flex, and the resulting jams when fired for extended periods of time. Likewise, the trunnion and barrel was made heavier and extensively lined with chrome.
The weapon fired from a closed bolt at a rate of 600-rounds per minute. To help keep that rate of fire up, the guns could use a much longer 40-round super banana mag or a 75-round drum besides just the standard 30-round AK mags. A distinctive clubfoot buttstock and folding underbarrel bipod reminiscent of the preceding BAR helped control the RPK in a prone position and keep its huge magazine out of the mud.\
When compared to its 6.5-pound, 35-inch long AK little brother, the 10.6 pound, 40.9-inch long RPK was a good bit larger. Few parts interchanged between the two but the two guns used similar manipulation and cleaning procedures, which eased cross training.
The RPK was, as planned, issued down to the squad level in Soviet motorized rifle, airborne and naval infantry units starting in 1961. The Soviets and their allies who received/made their own were very active over the 1960s and 70s which meant the RPK saw a lot of use in some pretty primitive places. The fact that the RPK is a super beefed up AK, which was no slouch in reliability itself, translated to a gun that was extremely durable in field service. While heavy to lug around all day, when the bullets started humming it became many an Ivan’s best friend.
In the late 1970s, the AK itself was redesigned to fire the smaller 5.45x39mm cartridge. With the change in caliber size, the RPK was likewise shrunk to accept this new round—just in time for use in Afghanistan in the 1980s and the wars in Chechnya that followed. This current RPK74M model is the standard squad automatic rifle is Russian/Ukrainian service. With plastic furniture, a folding buttstock, and polymer magazines, it is very distinctive. When folded it is a compact 33.87-inches long but still weighs a brutal 10.47-pounds without its 45-round magazine inserted. Still it is popular and shows no sign of being replaced.
US troops have encountered the RPK and its variants in the field for more than thirty years in the hands of Vietnamese, Iraqi, Muj, et al. While we can’t guess where US troops will be thirty years from now, odds are they will find the RPK there too if past history serves as a reference.
Semi-auto US versions
Foreign military hardware is always a hit in the US so of course the RPK has a big fan club in the states. Century Arms, masters of the concept of taking US-built receivers and adding them to imported parts kits to make semi-auto imitations of foreign guns, has long marketed 7.62x39mm RPK clones. First, it was the M-72, a gun made from the Yugo RPK. Later they moved to the (unpopular) Romanian AES-10A, which were made with thinner receivers and barrels to varying degrees of quality. More recently, they switched to a heavier chrome lined barrel used on actual Cugir RPK kits marketed as the AES-10B. Field reports on the “B” models seem to come in fairly nice for a semi-auto version of a squad rifle. Before December 2012, they ran about $550.
Both Inter Ordanance (IO) and Arsenal SA (as the RPK-7R) made versions on top quality receivers with ‘virgin’ parts kits. These guns are generally considered to be the Cadillacs of monster AKs and run 2-3x the price in consequence. Particularly nice models have CNC milled Warrior or Heese receivers which are probably a step up from the original Izhmash design.
Bulgarian, Yugo, and Rumanian parts kits for both the RPK and RPK74 are another option to build a dummy gun or your own working model from a fresh receiver. Just beware that most Romanian parts kits have super worn barrels and others are lacking the trunnion. Using a standard AK trunnion rather than the heavier RPK one often leads to headspacing issues so be sure to come correct on your home build or have good health insurance.
No matter what, it seems this goliath AK is here to stay.