Machine pistols are submachine guns that can be used with one hand. They, and the SMG class they inherit from, differ from machine guns in that they use pistol ammunition. Not just alike in calibre; the ammunition is identical. Pistol ammunition usually carries a smaller charge than rifle or machine gun ammunition in order to allow one-hand operation as well as due to the fact that pistols swiftly become useless at medium to long range. This is due both to their short barrels and typically poor stabilization when fired.