The question, "Can I shoot .308 out of a 7.62x51?" is a common one, often leading to confusion and potentially dangerous situations. The short answer is: generally, yes, but with important caveats. While .308 Winchester and 7.62x51mm NATO cartridges look almost identical, there are subtle but significant differences that can affect firearm safety and accuracy. This article delves into those differences and explains why exercising caution is paramount.
Understanding the Differences: .308 Winchester vs 7.62x51mm NATO
Both .308 Winchester and 7.62x51mm NATO cartridges fire a bullet of approximately the same diameter (.308 inch). However, several key distinctions exist:
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Case Dimensions: The 7.62x51mm NATO cartridge case is slightly larger and has a different shoulder angle compared to the .308 Winchester case. This seemingly minor difference can lead to problems.
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Chamber Pressure: 7.62x51mm NATO cartridges generally operate at higher chamber pressures than .308 Winchester rounds. This higher pressure is designed for the stronger construction of 7.62x51mm NATO-specified rifles.
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Headspace: Headspace, the distance between the bolt face and the cartridge case head, is critical. A .308 Winchester round fired in a 7.62x51mm chamber might have excessive headspace, leading to inconsistent ignition, increased pressure, and potential malfunctions. Conversely, firing a 7.62x51mm round in a .308 chamber could result in a catastrophic chamber rupture.
Why You Should NOT Mix and Match (Usually)
Firing a .308 Winchester round in a rifle chambered for 7.62x51mm NATO is generally considered safe due to the larger chamber dimensions of the 7.62x51. However, this doesn't eliminate all risks:
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Accuracy Issues: The slightly looser fit can lead to decreased accuracy and inconsistent bullet performance.
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Damage to the Rifle: While unlikely with a single shot, repeated firing can lead to wear and tear on the chamber, potentially compromising its integrity.
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Manufacturer Recommendations: Always refer to the firearm manufacturer's guidelines. Some manufacturers explicitly prohibit the use of .308 Winchester in their 7.62x51mm rifles, while others may permit it with specific warnings and disclaimers regarding liability. Never disregard manufacturer's warnings.
Firing a 7.62x51mm NATO round in a rifle chambered for .308 Winchester is extremely dangerous and should be absolutely avoided. This combination risks:
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Chamber Rupture: The higher pressure of the 7.62x51mm round may exceed the strength limits of a .308 Winchester chamber, leading to a catastrophic failure that can cause serious injury or death. This is a very real and serious danger.
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Bolt Failure: The pressure could also damage the bolt and other critical parts of the firearm.
Case Study: A Near Miss
In a discussion forum related to firearms, a user described firing a 7.62x51mm round in a rifle mistakenly believed to be chambered for .308. The result was a bulging chamber, requiring extensive repairs to the rifle. This situation underscores the potential consequences of mismatched ammunition.
What to Do?
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Always Double-Check Your Ammunition: Verify the caliber markings on both the ammunition and the firearm before every single shooting session.
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Read the Manual: Consult your firearm's owner's manual for explicit guidance on permitted ammunition types.
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If Unsure, Don't Shoot: When in doubt, err on the side of caution and seek advice from a qualified firearms expert before attempting to fire any ammunition.
Conclusion: Safety First!
While seemingly minor, the differences between .308 Winchester and 7.62x51mm NATO cartridges can have significant consequences. Prioritizing firearm safety and always adhering to manufacturer's recommendations is crucial to prevent accidents and ensure safe shooting practices. The potential for catastrophic firearm failure is real and warrants extreme caution. Never compromise your safety or the safety of others by mismatching ammunition and firearms.