International Standard Atmosphere
For a typical .375 CheyTac chambered gun, shooting 24.30 gram (375 gr) Lost River Ballistic Technologies bullets (claimed G1 BC = 1.02) at 930 m/s (3050 ft/s) muzzle velocity, the supersonic range would be 2230 m (2440 yd) under International Standard Atmosphere sea level conditions (air density ρ = 1.225 kg/m3).