30 caliber

The 7.62 mm caliber is a nominal caliber used for a number of different cartridges. Historically, this class of cartridge was commonly known as .30 caliber, the equivalent in Imperial and United States Customary measures. It is most commonly used in hunting cartridges. The measurement equals 0.30 inches or three decimal lines, written .3″ and read as three-line.The 7.62 mm designation refers to the internal diameter of the barrel at the lands (the raised helical ridges in rifled gun barrels). The actual bullet caliber is often 7.82 mm (0.308 in), although Soviet weapons commonly use a 7.91 mm (0.311 in) bullet, as do older British (.303 British) and Japanese (7.7×58mm Arisaka) cartridges.

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