The .30-06 Springfield cartridge (pronounced “thirty-aught-six” or “thirty-oh-six”), 7.62×63mm in metric notation and called “.30 Gov’t ’06” by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in use until the early 1980s. The “.30” refers to the caliber of the bullet in inches. The “06” refers to the year the cartridge was adopted—1906. The .30-06 remained the U.S. Army’s primary rifle and machine gun cartridge for nearly 50 years before being replaced by the 7.62×51mm NATO (commercial .308 Winchester) and 5.56×45mm NATO, both of which remain in current U.S. and NATO service. It remains a very popular sporting round, with ammunition produced by all major manufacturers.