Generally, the .357 Magnum will push bullets of the same weight about 30 percent faster than the 9mm Luger. This also translates to more energy; .357 Magnum loads can hit as much as 70 percent harder.

Technically Speaking For two cartridges that fire bullets of an almost identical diameter, the .357 Magnum (0.357-inch) and the 9mm Luger (0.355-inch) could not be more different.