The .30-03 is a rifle cartridge developed in the early 1900s, primarily for military use. It was designed to improve upon the earlier .30-40 Krag cartridge, offering better performance and accuracy. The .30-03 features a bullet diameter of .308 inches and was initially used in the Springfield M1903 rifle. Although the .30-03 was eventually replaced by the more popular .30-06 Springfield cartridge in 1906, it played a significant role in the evolution of military ammunition. The .30-06 offered enhanced range and power, becoming the standard for the U.S. military for several decades.