Can You Shoot 7.62 In .308
Can You Shoot 7.62 In .308
The debate surrounding the interchangeability of 7.62x51mm NATO and .308 Winchester ammunition is one of the most persistent topics in the firearms community. For many shooters, the two cartridges appear identical to the naked eye, leading to the common question: can you shoot 7.62 in .308? The short answer is yes, but the reverse is not always true. Understanding the subtle yet critical differences in pressure, headspace, and case construction is essential for any gun owner looking to maintain the longevity of their firearm and ensure personal safety. This guide explores the technical nuances between these two popular rounds and provides a definitive look at how they interact with different rifle chambers.
The Technical Differences Between .308 Winchester and 7.62x51mm NATO
While the .308 Winchester and the 7.62x51mm NATO share nearly identical external dimensions, they are not the same cartridge. The .308 Winchester was introduced by Winchester in 1952 as a commercial hunting round, while the 7.62x51mm NATO was developed as a standardized military round for semi-automatic and fully automatic battle rifles. Because their purposes differed, their manufacturing specifications also diverged in two major areas: chamber pressure and headspace.
In the world of commercial ammunition, the Sporting Arms and Ammunition Manufacturers Institute (SAAMI) sets the standards. SAAMI rates the maximum pressure for .308 Winchester at 62,000 PSI. Conversely, the military specifications for 7.62x51mm NATO generally result in a lower maximum pressure, often cited around 60,000 PSI or lower when measured using modern piezoelectric sensors. Furthermore, military brass is typically thicker than commercial brass. This extra thickness is necessary for the violent extraction cycles of military firearms, but it reduces the internal volume of the case, which can lead to higher pressures if the case is reloaded with .308 Winchester powder data.
Headspace is the other critical factor. Military chambers for the 7.62x51mm NATO are intentionally cut longer and "looser" to ensure that the rifle will continue to feed and extract reliably even when dirty or subjected to the heat of rapid fire. Commercial .308 Winchester chambers are cut to tighter tolerances to maximize accuracy. When you fire a 7.62 NATO round in a .308 chamber, it generally fits perfectly because it is the "smaller" or lower-pressure specification. However, firing a .308 Winchester in a 7.62 NATO chamber can be risky, especially in older military surplus rifles, because the thinner commercial brass may stretch too far in the longer military chamber, leading to a potential case head separation.
Interchangeability and Safety Guidelines
When discussing whether you can shoot 7.62 in .308, safety should always be the priority. Most modern firearms chambered in .308 Winchester are over-engineered to handle the pressures of both rounds. Because the .308 Winchester is the higher-pressure round, a rifle built to withstand it will safely handle the lower-pressure 7.62 NATO round. This is a general rule that applies to most modern bolt-action rifles and precision platforms.
| Comparison Feature | .308 Winchester |
|---|---|
| Maximum SAAMI Pressure | 62,000 PSI |
| Common NATO Pressure | ~60,000 PSI |
| Case Wall Thickness | Thinner (Commercial) |
| Chamber Tolerance | Tighter (Precision) |
However, if you own a rifle specifically marked 7.62x51mm NATO, such as an older M14, FN FAL, or military surplus bolt-action, you must be cautious. These rifles were designed for the specific pressure curve and thicker brass of military ammunition. Using "hot" commercial hunting loads in these older platforms can lead to excessive wear on the action, blown primers, or even catastrophic failure. Always check the barrel stamping or the manufacturer's manual to confirm which rounds are recommended for your specific firearm.
Performance and Accuracy Considerations
Beyond the safety aspect, shooters often wonder about the performance differences between the two. Generally, 7.62x51mm NATO is found as "ball" ammunition, such as the M80 load, which uses a 147-grain or 150-grain full metal jacket (FMJ) projectile. This ammo is intended for general military use and is not typically designed for sub-MOA accuracy. If you are shooting 7.62 NATO through a high-end .308 Winchester precision rifle, you may notice that your groups are larger than they would be with match-grade .308 ammo.
Additionally, the primer on military 7.62 NATO rounds is often harder (mil-spec) to prevent "slam fires" in semi-automatic rifles. Some commercial .308 rifles with lighter target triggers or weakened firing pin springs might occasionally fail to ignite these harder primers. While this is rare in modern bolt guns, it is something to keep in mind if you experience light strikes while using surplus military ammunition in a commercial rifle.
FAQ about Can You Shoot 7.62 In .308
Is 7.62x51mm NATO exactly the same as .308 Winchester?
No, they are not exactly the same. While their external dimensions are nearly identical, the .308 Winchester has a higher maximum pressure rating and uses thinner brass compared to the 7.62x51mm NATO, which has thicker brass and a longer headspace tolerance.
Will shooting 7.62 NATO damage my .308 rifle?
In most modern rifles chambered for .308 Winchester, shooting 7.62 NATO will not cause any damage. Since .308 is the higher-pressure cartridge, the rifle is designed to handle more stress than the 7.62 NATO round typically generates.
Can I shoot .308 Winchester in a 7.62x51mm rifle?
You should exercise caution. While many modern 7.62 rifles can handle .308, older military surplus rifles may have headspace issues or actions that are not designed for the higher pressures of commercial .308 hunting rounds. Always consult the manufacturer.
Which cartridge is better for hunting?
.308 Winchester is generally better for hunting because there is a much wider variety of expanding, high-performance projectiles available. Most 7.62 NATO is FMJ "ball" ammo, which is not suitable or legal for hunting in many jurisdictions.
Conclusion
In conclusion, the question of "can you shoot 7.62 in .308" can be answered with a confident yes for the vast majority of modern shooters. Because the .308 Winchester is the higher-pressure specification, rifles chambered for it are more than capable of handling the lower-pressure 7.62x51mm NATO rounds. The primary differences lie in the internal case volume and the headspace tolerances of the rifles themselves. While you can enjoy the cost savings of surplus 7.62 NATO for target practice in your .308 rifle, always remember to verify the specific requirements of your firearm, especially if you are using older military surplus equipment. Staying informed about these technical details ensures that your time at the range remains safe, enjoyable, and productive.