The 6P62 is a beast of a gun. It is a magazine fed machine gun that chambers the Russian 12.7x108mm cartridge, a round that is slightly more powerful than a .50 BMG.
Its short barrel reduces the velocity of the 12.7mm ammunition to 2099 fps (down from the 2800 fps of a standard anti-material gun). The decrease in velocity results in a 44% decrease of energy but at 7847 ft/lbs of energy it is still considerably powerful.
It weights 33 lbs unloaded, fires at 400-500 rpm and is 47″ in length.
It was never adopted by any armed forces. If such a powerful shoulder fired gun was needed, a much more efficient cartridge would probably be designed.
[ Many thanks to Val for emailing me the info. ]Related