Can You Shoot .308 Out of a 7.62x51? Understanding the Subtle Differences
The short answer is: generally, yes, but with important caveats. The .308 Winchester and 7.62x51mm NATO cartridges are very similar, leading to much confusion. However, while they share the same bullet diameter (.308 inch), there are key differences that affect interchangeability. Let's delve deeper.
The Similarities: A Shared Bullet Diameter
Both .308 Winchester and 7.62x51mm NATO cartridges fire a .308 inch diameter bullet. This is where the interchangeability notion stems from. Many shooters have successfully fired .308 rounds from rifles chambered for 7.62x51mm without immediate catastrophic failure.
The Crucial Differences: Chamber Dimensions and Pressure
The critical distinction lies in the chamber dimensions and maximum pressure. While the bullet diameter is the same, the 7.62x51mm NATO cartridge case is slightly larger and designed to handle higher pressures.
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Chamber Dimensions: The 7.62x51mm NATO chamber is slightly larger than the .308 Winchester chamber. This means a .308 round will generally fit into a 7.62x51mm chamber. However, there's potential for the round to be loosely seated, leading to potential accuracy issues.
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Pressure: The 7.62x51mm NATO round is designed to withstand significantly higher pressures than the .308 Winchester round. This difference is crucial. Firing a 7.62x51mm round in a .308 Winchester chamber is incredibly dangerous and can cause catastrophic failure of the firearm, resulting in serious injury or death. Conversely, while firing a .308 round in a 7.62x51mm chamber might seem safe, it's not without potential risks.
Potential Risks of Interchangeability
While often successful, firing .308 Winchester rounds from a 7.62x51mm chamber is not without risks:
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Accuracy Issues: The loose fit within the chamber can lead to inconsistent accuracy and potentially dangerous deviations in projectile trajectory.
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Case Head Separation: Repeated firing of .308 rounds in a 7.62x51mm chamber might, over time, weaken the brass, potentially leading to case head separation. This can cause serious damage to the firearm and result in injury.
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Manufacturer Recommendations: Always check the firearm manufacturer's recommendations before attempting to fire any ammunition that is not explicitly stated to be compatible.
The Bottom Line: Proceed with Extreme Caution (or Not at All)
While the .308 Winchester and 7.62x51mm NATO cartridges seem interchangeable due to their shared bullet diameter, the differences in chamber dimensions and maximum pressure should never be ignored. Firing .308 rounds in a 7.62x51mm chamber might work, but it carries potential risks to accuracy and firearm safety. The safer and strongly recommended practice is to only fire the ammunition specifically recommended by the firearm manufacturer. Ignoring this advice could lead to serious injury or damage to your firearm. Safety should always be the top priority.
