Are .308 and 7.62x51mm the Same Caliber?

The question of whether the .308 and 7.62x51mm caliber are the same often arises among shooters and enthusiasts. To address this query comprehensively, it's important to understand the various cartridges and metrics involved.

Introduction to 7.62 Rounds

The 7.62 caliber is a range of cartridges measuring 7.62 millimeters in diameter. These rounds include a variety of standards and measurements, from the early 7.62x25 Tokarev to modern NATO standards. Among the most well-known are the 7.62x39 Soviet, 7.62x51 NATO, and 7.62x54R Russian cartridges, each designed for specific applications and platforms.

Key Differences in Caliber

The confusion often stems from the fact that the 7.62x51mm NATO and .308 Winchester refer to the same diameter (0.308 inches) but can be chambered in different cartridges with varying pressures and specifications. This is why they appear to be the same caliber but are actually different cartridges.

Understanding the .308 Winchester

The .308 Winchester is a versatile cartridge used widely for hunting and precision shooting. It measures exactly 0.308 inches in diameter and is part of the standard system of measurements, commonly used in the United States. Despite this, the .308 Winchester can be found in various chamberings, including the 7.62x51mm NATO, which is a metric equivalent of 7.62 millimeters in diameter.

No Common Cartridge

It’s important to note that while the 7.62x51mm NATO and .308 Winchester share the same diameter, they are not interchangeable without risking damage to the rifle or the shooter. The key differences lie in the pressures, chamber dimensions, and intended use:

7.62x51mm NATO: Designed for military and high-powered hunting applications, this cartridge is noted for its high-pressure capabilities. .308 Winchester: A civilian cartridge used for hunting and precision shooting, it is chambered at lower pressures than the NATO standard.

Common Cartridges in the 7.62mm Range

Given the variation in 7.62mm cartridges, a complete list includes:

7.62x25 Tokarev: Used in Soviet-made pistols and other carbines, with a 309 bullet. 7.62x35: Known as the 300 AAC Blackout, with a 308 bullet. 7.62x39 Soviet: Used in the AK-47 family, with a 311 bullet. 7.62x51 NATO: Chambered in military rifles, with a 308 bullet. 7.62x53 Argentine: Also known as Mauser, with a 313 bullet. 7.62x54R Soviet: A rimmed cartridge, with a 312 bullet. 7.62x63 .30–06 Springfield: Metric notation for the .30–06 caliber, with a 308 bullet. 308 Winchester: Standard hunting cartridge, with a 308 bullet.

Chambering Considerations

While .308 Winchester cartridges can fit into a 7.62x51mm NATO chamber, it is not advisable to do the reverse. Modern military rifles, such as the M14, are chambered for the 7.62x51mm NATO and are rated to handle the higher pressures associated with this cartridge. Attempting to shoot .308 Winchester in a rifle rated for 7.62x51mm NATO could result in equipment damage and potential safety hazards.

Visual Differences

Some 7.62mm cartridges, like the 7.62x39 and 7.62x54R, have distinct visual cues such as length and a rim, making them easy to identify. However, the 7.62x51mm NATO and .308 Winchester are visually indistinguishable, requiring careful attention to the rifle’s chambering rating to ensure correct ammunition is used.

Conclusion

While the 7.62x51mm NATO and .308 Winchester share the same diameter, they are not the same cartridge due to differences in pressure, chamber design, and intended use. Understanding these differences is crucial for safe and effective rifle usage. When in doubt, always check the rifle’s specific chambering and stick to the correct ammunition for your firearm.