14.5x114mm 

HUGE anti-tank round developed by the Soviets in WWII. It is larger and more powerful than the mighty .50 BMG cartridge, though it is almost non-existent in the Western World and other non Warsaw Pact countries. The PTRS-41 anti-tank rifle in Call of Duty: World at War is chambered for this caliber, although it is inaccurately portrayed as a mobile "sniper rifle." The rifle's inclusion in the game can be justified somewhat due to the supposed necessity of a WWII "equivalent" of the popular Barrett M82 in Call of Duty 4. Some claim that the sniper rifle in Halo is chambered in 14.5mm.

14.5x114mm rounds are pretty freaking huge. Getting a rare opportunity to shoot one would be quite an experience.

14.5x114mm by WALTHERMAN March 30, 2010