The .300 Winchester Short Magnum is a 7.62mm short action magnum cartridge with considerable effect. It is very similiar to the regular .300 Winchester Magnum in terms of ballistics, but takes advantage of the short action design which allows more powder to sit closer to the flash hole. When the primer ignites, it allows a more uniform burn which in turn translates into more efficient use of energy. A 300 WSM can therefore achieve the same ballistics with less powder.