It is based on the .30-06 Springfieldcatridge. The bullet is the same size, but the case is slightly smaller so soldiers could carry more bullets. It was the main bullet used by NATO until the 5.56×45mm NATO was invented.
Guns that use the 7.62 NATO include the M14, the FN FAL, the G3, the SCAR, the M240, and the M21.