Can You Shoot .308 Through a 7.62x51mm? Understanding Cartridge Compatibility
The question of whether you can shoot a .308 Winchester round through a 7.62x51mm NATO rifle is a common one, and the short answer is generally yes, but with significant caveats. While the two cartridges are very similar in terms of bullet diameter, there are crucial differences that can lead to serious consequences if ignored.
The Similarities: Bullet Diameter and Function
Both the .308 Winchester and the 7.62x51mm NATO rounds fire a .308 inch diameter bullet. This means the projectile itself will likely fit down the bore of either rifle. Functionally, both cartridges are designed for similar purposes: long-range accuracy and stopping power.
The Critical Differences: Case Dimensions and Pressure
The critical differences lie in the cartridge cases themselves. While the bullet diameter is nearly identical, the 7.62x51mm NATO case is slightly larger and longer than the .308 Winchester case. This seemingly minor difference results in key distinctions:
-
Headspace: The headspace (the distance between the bolt face and the cartridge case head) is crucial. A .308 Winchester round fired in a 7.62x51mm rifle might have excessive headspace, leading to inconsistent ignition and potentially dangerous pressure increases.
-
Chamber Pressure: 7.62x51mm NATO rounds are designed to operate at higher chamber pressures than .308 Winchester rounds. Firing a .308 round in a 7.62x51mm chamber may not always result in overpressure, but it could result in inconsistent accuracy and potential damage to the rifle over time.
-
Case Strength and Material: While often overlooked, slight variations exist in the materials and manufacturing processes of the cartridges. This can further affect pressure and overall reliability.
The Risks of Mixing Cartridges
Attempting to fire .308 Winchester rounds in a 7.62x51mm NATO rifle could work without immediate catastrophic failure, especially in modern, well-maintained rifles. However, this practice is strongly discouraged due to the increased risk of:
-
Increased Pressure: Even if the bullet fits, the potentially larger case volume of the 7.62x51mm chamber combined with the slightly lower pressure of .308 ammunition might lead to irregular chamber pressure. Consistent overpressure risks catastrophic rifle failure.
-
Inconsistent Accuracy: Variations in headspace and pressure will almost certainly negatively impact accuracy.
-
Damage to the Rifle: Over time, continuous use of .308 Winchester ammunition in a 7.62x51mm rifle can wear the chamber, potentially leading to future malfunctions and dangerous pressure spikes with the intended 7.62x51mm ammunition.
The Safe Approach: Cartridge-Specific Rifles
The safest and most reliable approach is to use the correct ammunition for the specific firearm. Always consult the firearm's owner's manual for specific recommendations on the ammunition it is designed to handle. Mixing and matching cartridges can be extremely dangerous and should be avoided. This is not just a matter of accuracy; it is a matter of safety. Using the wrong ammunition could cause severe injury or death.
Disclaimer: This information is for educational purposes only. Always consult a firearms expert or your firearm’s owner’s manual before attempting to use any ammunition in a firearm. Improper handling of firearms and ammunition can lead to serious injury or death.
