In mid-2016 Russia introduced the RPK-16, a new LMG (light-machine-gun) to replace the current RPK-74. The RPK-16 weighs 6 kg (13.2 pounds) loaded, compared to 6.8 kg for the RPK-74 and is also easier to handle and uses the same 5.45×39mm round and magazines (30 or 96 round) as the RPK-74. Like Western LMGs the RPK-16 has a Picatinny rail for accessories and can use a suppressor.
This all began in 1961 when the first RPK was introduced. This was basically a heavier (4.8 kg/10.6 pounds) variant of the 3.47 kg (7.7 pound) AK-47 and used the same 7.62X39 ammunition. RPK had a bipod and could use AK-47 magazines but in different sizes (20, 30 or 40 rounds) or a drum magazine with 75 rounds. The standard 30 round magazine weighed 1.2 kg (2.6 pounds) so the RPK with the larger 75 round drum magazine only weighed 7.4 kg (16.3 pounds). The RPK had a longer and heavier barrel that barrel could not be quickly replaced when it got overheated. This was an innovation the Germans introduced during World War II. While the Russians recognized the effectiveness of the “quick change” barrel they felt it was more practical to train their troops to fire short bursts and pay attention to barrel overheating. That meant the practical rate of fire for the RPK was about 80 rounds a minute compared to more than 200 rounds a minute for machine-guns with a quick change barrel. It wasn’t until the RPK-16 showed up that it became possible to easily switch barrels on an RPK.
In 1984 the U.S. caught up with Russia by introducing the M249. This weapon was based on the Belgium Minimi which in turn was a better version of the various “heavy M-16 light machine-guns” (similar in concept to the RPK) proposed throughout the 1960s. The Minimi entered service in Europe by 1975 but it wasn’t adopted by the United States as the M249 until 1982. The M249 fired the same 5.56×45mm round as the M-16 but could handle M-16 magazine as well as belt-feed (usually from a 200 round belt from a box attached to where the magazine usually went). The Russians noted the greater effectiveness of the 5.56×45mm round and in 1974 introduced 5.45×39mm versions of the AK-47 (as the AK-74 and RPK-74,)
One thing the Russians have still not adopted is the Western concept of the LMG being the key weapon for the infantry squad. During World War II the Russians found it much more effective to simply equip most troops with a weapon that could fire on automatic. Until the late 1940s this was done with Russian submachine guns. German troops got a shock when they encountered masses of Russian troops armed with the PPD submacinegun. This weapon fired the relatively weak 7.62x25 round, which was basically a pistol round. The bullet from the 7.62x25 would more often wound than kill, and it took several hits to definitely bring down an enemy soldier. But a few hundred Russian troops armed with the PPD (usually equipped with a 71 round drum magazine), firing at German positions, certainly caused the Germans to keep their heads down. The more powerful 7.92x33 German assault gun round was more likely to hurt the victim, and better at shooting through walls, doors and floors. After World War II, Russia developed the AK-47, and used the 7.62x39 round they already had. The 7.62x39 had similar performance to the Sturmgewehr 44s 7.92x33 round. The AK-47 was more durable, and cheaper to manufacture. While the West went on to develop more effective LMGs the Russians were satisfied with equipping all their infantry with the AK-47. That changed when the Russians noted that modern warfare was dominated by armies that had trained most of their troops to accurately fire their assault rifles one shot at a time, using automatic fire very rarely and also depending on lightweight LMGs with quick-change barrels for sustained fire.