In 2001 Remington introduced their .375 Remington Ultra Mag, which is based on the .300 Ultra Mag case necked up to accept .375" diameter bullets. Like the .300 Ultra Mag, this huge beltless cartridge is loosely based on the British .404 Jeffery Rimless elephant rifle case, and uses a rebated rim design to allow it to mate with standard magnum size bolt faces. The .375 Ultra requires a long magnum action. Remington factory loads include a 270 grain bullet at a claimed muzzle velocity (MV) of 2,900 fps and 5,041 ft. lbs. of muzzle energy (ME), and a 300 grain bullet at a MV of 2,760 fps and ME of 5073 ft. lbs. At 200 yards the 300 grain bullet is traveling at 2263 fps and retains 3412 ft. lbs. of energy. These figures were developed in a 24" test barrel. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.