The M1903 Springfield, officially the U. S. Rifle, Caliber .30, M1903, is an American five-round magazine-fed, bolt-action service repeating rifle, used primarily during the first half of the 20th century.

A magazine, often simply called a mag, is an ammunition storage and feeding device for a repeating firearm, either integral within the gun or externally attached. The magazine functions by holding several cartridges within itself and sequentially pushing each one into a position where it may be readily loaded into the barrel chamber by the firearm's moving action. The detachable magazine is sometimes colloquially referred to as a "clip", although this is technically inaccurate since a clip is actually an accessory device used to help load ammunition into a magazine or cylinder.