International Standard Atmosphere
According to JBM Ballistics, using the G7 ballistic coefficient provided by Bryan Litz, and a Weapon Employment Zone (WEZ) analysis of the XM2010 rifle with various .300 Winchester Magnum ammunition types by Bryan Litz, the MK 248 MOD 1 .300 Winchester Magnum cartridge, when fired at its nominal muzzle velocity of 869 m/s (2,850 ft/s), should have supersonic range under International Standard Atmosphere conditions at sea level (air density ρ = 1.225 kg/m3).