Can You Shoot 7.62x51mm NATO Out of a .308 Winchester Barrel? The Complex Answer
The short answer is: generally yes, but with significant caveats. The longer answer requires a deeper dive into the nuances of these two cartridges. While seemingly interchangeable, the 7.62x51mm NATO and the .308 Winchester cartridges have subtle but crucial differences that can impact firearm safety and accuracy.
Understanding the Differences: 7.62x51mm NATO vs. .308 Winchester
Both cartridges share the same basic dimensions, leading to the common misconception of complete interchangeability. However, the 7.62x51mm NATO round is designed to withstand higher chamber pressures. This means:
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Chamber Pressure: 7.62x51mm NATO operates at higher chamber pressures than .308 Winchester. Firing a 7.62x51mm round in a barrel chambered only for .308 Winchester can lead to catastrophic failure. The .308 Winchester chamber is often slightly smaller, potentially causing dangerous pressure build-up.
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Case Head Dimensions: While subtle, there are minor differences in case head dimensions. These small variations can cause the 7.62x51mm round to not properly seat in a .308 Winchester chamber. This can lead to misfires, or even worse, a dangerous bulge in the casing.
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Rifling: While both use similar rifling, minor differences can exist between manufacturers, impacting accuracy and potentially causing increased wear on a .308 Winchester barrel if used extensively with 7.62x51mm ammunition.
The Risks of Interchangeability
Firing 7.62x51mm NATO ammunition in a firearm chambered for .308 Winchester carries significant risks:
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Barrel Burst: The increased chamber pressure of the 7.62x51mm round can exceed the design limits of the .308 Winchester barrel, leading to a catastrophic barrel rupture. This is extremely dangerous, potentially causing serious injury or death.
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Action Damage: The increased pressure can also damage the firearm's action, rendering it unusable and potentially unsafe for future use.
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Reduced Accuracy: Even if the round fires without catastrophic failure, the dimensional differences can lead to inconsistent accuracy and potentially damage the barrel over time.
When Interchangeability Might Be Acceptable (Proceed with Extreme Caution)
Some manufacturers claim that their .308 Winchester barrels are "capable" of handling 7.62x51mm NATO ammunition. However, this should never be considered a guarantee. Even in these instances, it is highly recommended to:
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Consult the manufacturer's specifications: Carefully review the manufacturer's instructions and documentation to explicitly confirm whether or not your specific firearm and barrel are rated for 7.62x51mm NATO.
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Inspect the barrel after every firing: Look for signs of bulging or damage after every shot. Any visible damage is a clear indicator to cease firing immediately.
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Use only high-quality ammunition: The quality of the 7.62x51mm ammunition used can affect chamber pressure, so ensure it meets stringent standards.
Conclusion: Safety First
While some argue that the difference is negligible, the potential for catastrophic failure when firing 7.62x51mm NATO in a .308 Winchester barrel is too high to risk. The safest course of action is to always use ammunition specifically designed for the chambering of your firearm. Ignoring this precaution could have devastating consequences. Always prioritize safety when handling firearms.
