7.62mm NATO

From The D Archives

NATO's 7.62x51mm rifle cartridge, commercially known as .308 Winchester, was introduced in the 1950s as a standard firearm cartridge among NATO countries, though it has also become popular among civilians. The round is produced by many manufacturers in types that include tracers and blanks.

The military 7.62x51mm cartridge is nearly identical to the commercial .308 Winchester. NATO controls specifications for the military round while SAAMI controls specifications for the civilian round. The organizations have established two differences: the standard pressure is 50,000 psi, as measured by the copper crusher gauge, for most military rounds, while the SAAMI maximum is 62,000 psi, measured with a piezoelectric gauge, for the civilian round. Since the two types of gauges give different pressure readings, the two pressures cannot be accurately compared. The NATO M60 High Pressure Test round is loaded to a pressure of 67,500 psi, so military arms should be capable of handling the pressure of civilian rounds. The military chamber is specified to be 1.645 inches, compared to the civilian chamber of 1.632 inches. Though this difference is just 0.013 inches,[2] a chamber of acceptable military length will put excessive stress on the thinner civilian brass, causing premature head separation. While it is safe to mix .308 and 7.62x51mm ammunition, fewer problems will be encountered if the correct caliber designation is used.

The 51mm-long case of the 7.62x51mm NATO/.308 Winchester, when necked down to accept bullets of 7mm, 6.5mm and 6mm diameters respectively, has given birth to three popular and successful sporting cartridges, the 7mm-08 Remington, the .260 Remington and the .243 Winchester.