Hello, I'm an expert in firearms and ballistics. Let's address your question about firing a 7.62mm round from a .308 caliber firearm.

It's important to understand that 7.62mm and .308 caliber are not the same, although they are often confused because the measurements are similar. The 7.62mm round is a metric measurement, while .308 is an imperial measurement. In reality, a .308 caliber is slightly larger than 7.62mm. The .308 Winchester, for example, has a bullet diameter of about 7.85mm (0.308 inches), which is larger than the 7.62mm NATO round.

Using a 7.62mm round in a firearm chambered for .308 could result in a loose fit, which can cause the bullet to not engage the rifling properly, potentially leading to inaccurate shooting and even dangerous situations. It's also possible that the case dimensions could be different, which can lead to feeding issues or increased pressure if the firearm is not designed to handle the specific characteristics of the 7.62mm round.

In conclusion, while the measurements are close, a 7.62mm round should not be used in a .308 caliber firearm without first ensuring that the specific firearm is designed to safely accommodate that round. It's always best to use the ammunition for which the firearm was designed and manufactured.

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The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62��51 max is 50,000 psi. Also, the headspace is slightly different. ... That said, it is normally fine to shoot quality 7.62��51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical).read more >>