Can You Shoot 7.62x51 in a .308 AR-10? The Crucial Differences and Potential Dangers
The short answer is: generally no, you should not shoot 7.62x51mm NATO ammunition in a rifle chambered for .308 Winchester. While the cartridges look similar and share the same basic dimensions, there are key differences that can lead to serious injury or damage to your firearm.
Let's delve into the specifics to understand why this is such a crucial safety consideration.
Understanding the Subtle, Yet Significant Differences
Both 7.62x51mm and .308 Winchester are commonly referred to as ".308 caliber," but this is where the simplicity ends. While the bullet diameter is virtually the same, the crucial distinctions lie in:
-
Chamber Dimensions: The 7.62x51mm NATO cartridge has slightly larger chamber dimensions than the .308 Winchester. This seemingly small difference is significant. Firing a 7.62x51mm round in a .308 Winchester chamber can result in:
- Overpressure: The larger cartridge can create excessive pressure within the smaller chamber, potentially leading to catastrophic failure of the rifle. This can cause serious injury to the shooter and bystanders from parts of the firearm exploding.
- Case Head Separation: The increased pressure can cause the cartridge case to separate at the base, potentially jamming the firearm and causing damage.
- Bullet Obstruction: The slight dimensional difference might cause the bullet to become lodged in the barrel before it leaves the firearm.
-
Cartridge Case Material and Construction: Variations in the cartridge case material and construction between 7.62x51mm and .308 Winchester can further exacerbate the pressure issues. The NATO spec cartridge is often made to more stringent tolerances and with different materials, and might not be able to withstand the pressure inside the smaller chamber.
-
Headspace: The distance between the bolt face and the breech face (headspace) is critical. A difference in headspace between a rifle chambered for .308 Winchester and one chambered for 7.62x51mm can make the pressure situation even more dangerous.
Why the Risk Isn't Worth It
While some claim that they've fired 7.62x51mm in their .308 AR-10 rifles without incident, this is a gamble with potentially devastating consequences. The slight difference in chamber dimensions is enough to introduce a dangerous level of risk. It’s not a matter of "if" but "when" a problem might arise. Even with a few successful firings, the eventual failure could lead to irreparable damage or significant injury.
The Safe Practice: Stick to the Manufacturer's Specifications
Always use ammunition that precisely matches the chamber specifications of your firearm. Check your rifle's manual for the explicitly stated ammunition type. Never compromise on safety. The slight cost savings from using potentially incompatible ammunition is far outweighed by the risk.
Identifying Your Ammunition
Accurately identifying the ammunition you have is essential. Look for clear markings on the box and individual rounds. Make absolutely certain you are only using ammunition explicitly specified for your firearm.
In conclusion, while the temptation to use readily available 7.62x51mm in a .308 AR-10 might seem appealing, it is a practice that should be avoided at all costs. The potential for catastrophic damage and serious injury significantly outweighs any perceived benefit. Prioritize safety and always adhere to the manufacturer's recommendations.
