For all the the people out there that love the thrill of sniping this is the group for you
The one and only KSVK Russian counter-sniper rifle. This anti-material rifle exists for penetrating thick walls and lightly armored vehicles.
It uses the 12.7x108mm Warsaw Pact round, which means while it has the same diameter as the .50 Cal Browning Machine Gun, although the BMG is only 99mm long. This means the KSVK uses a bullet which is not only larger, but has more propellant behind it than a .50 cal.
so, uh... scary much?
(Sources: wikipedia.org and world.guns.ru)