The present Russian LMG is the RPK, 7.62X39 (meaning the round is 39mm long). It is really an enlarged AK assault rifle with a bi-pod taking either a 30 or 75 round magazine. It has a longer, heavier barrel but sustained fire is restricted in that there is no facility to change the barrelprobable rate of fire; 80 rounds per minute. It would appear a step backwards.
The US fielded the M60 (7.62X51) as its new general purpose MG in the early 60s. It used the MG42 feed system (later changed) and the locking system from the FG42. In the first model the barrel, gas cylinder and bipod were one unit necessitating an asbestos glove (Mitten, Asbestos, 1943) during a barrel change (when barrels can be as hot as 500 degrees.) Further, once the hot barrel (and bipod) was removed the gunner had to hold the gun in the air until his number 2 mounted a new one! This could turn into quit a trick if your partner was wounded or the glove was lost.
Most of the M60s short comings were alleviated over time but with the recent experience the US Army had in World War II e.g. the superb Bren, the exceptional MG42, one longs to see the SAT scores of the project officers.
Although the M60 remains in service, the marines became aware (darn those marines) of an FN design that the US had originally purchased for coaxial fire in armored vehicles i.e. the M240. The M60 and the M240 were tested: Two criteria; the Mean Time Between Stoppages (MTBS=stopped for less than a minute) and Mean Time Between Failures (MTBF=stopped for more than a minute). With both weapons firing 50,000 rounds the M60 score was MTBS = 846 and MTBF = 1,699 and the M240 scoring MTBS = 2,962 and MTBF = 6,442.
Disillusioned further with the firing restrictions on the light weight M60E3 the marines are replacing their M60s with the more reliable M240 (7.62x51), FN design; first getting their weapons on the surplus market then buying production models. The army is following suit (M240B). As reliable as Old Faithful, the M240 is a gas operated weapon that uses disintegrating link belt ammunition and is deployed with either a bipod or tripod.
In 1982 after much comparison testing, but finally in exchange for Belgium choosing the F-16 fighter, the US accepted another FN design, the Minimi, M249 as the squad automatic weapon (SAW), in 5.56mm. The M249 has proved to be a reliable gun that can fire from 30 round M16 magazines or 200 round belts in plastic magazines. It is, strictly speaking, an automatic rifle rather than a LMG and it takes the historical place of the BAR, M14 and M16E1. The barrel can be changed but astoundingly only with barrels head spaced (a minor adjustment made by the operator to improve performance) for the same gun! It is effective out to 800 meters and can be fired from the shoulder, hip (known as the John Wayne), bipod or tripod. The army tinkered around with this design until Desert Storm arrived, at which point they realized they had to make a quick purchase of 1000 more weapons!
In the 80s when the army accepted the Beretta M92 there were some problems. In at least two cases the recoiling slides broke free and hit the shooters in the face. There were several excuses, steel brought to too hard and brittle a level, etc.,. A later model, the M92FS or M9 had a pin put in to prevent such a recurrence. Accidents occurred like this at the beginning of the 20th century when steel metallurgy (Springfield receivers) was still relatively unsophisticated but to happen in the 1980s is akin to the Peace of God they passeth all understanding! Whats more this pistol was supposed to supplant the M1911 .45: A piece that serious shooters still choose ( Delta Force, Seals and last I heard, getting a very serious look from the FBI) when you absolutely must perform an instant attitude change in an enemy.
I am completely unable to account for this historical arc, careening from one mismanaged project to another, of weapons deployment by the US Army. The Lewis passed over for an ineffective French LMG. A pistol (M9) whose slide flies off: unheard of! A rifle (M16) so renowned for reliability that it was sold without a cleaning kit transformed by army ordnance into a late 20th century plastic club! A light machine gun (M60) so clumsy in design that one wonders if the committee that designed the Chauchat was back in charge, when the singular MG42 was available for free! A frivolous eight year delay in the full deployment of the M249!
The Johns, Browning and Grande must be spinning in their graves. Curmudgeon though I might be, is it any wonder that even the most objective observer would have serious questions about the eventual combat effectiveness of the OICW? --Peter38
The Machine-Gun: Five Un-Easy Pieces