Understanding the Differences Between 7.62x51 and .308 Caliber

What is 7.62x51 and .308? The same thing?

7.62x51 and .308 caliber are both rifle cartridges that are commonly used in AR-10 platform firearms, particularly in military and civilian applications. While they may seem interchangeable, it is essential to understand the differences between the two.

7.62x51 NATO is a powerful cartridge that was originally developed for the M14 rifle during the 1950s. It is a rimless, bottlenecked cartridge, meaning that the base of the cartridge is not significantly larger than the rest of the casing. This cartridge has a bullet diameter of .308 inches and is known for its excellent accuracy and long-range capabilities. It has since become widely popular and is now used in a variety of firearms, including the popular AR-10 platform.

Speaking of which, the AR-10 is a type of semi-automatic rifle that is compatible with the 7.62x51/.308 cartridge. It is known for its modularity, reliability, and ability to handle different calibers, including the 7.62x51/.308.

The .308 AR, on the other hand, refers to rifles that are specifically chambered for the .308 Winchester cartridge. These rifles are typically based on the AR-10 design, but there may be slight differences in dimensions and specifications, making them optimized for the .308 Winchester cartridge.

So, in summary, the 7.62x51 and .308 are essentially the same cartridge, with the latter being the commercial name for the military 7.62x51 cartridge. But can you use these two interchangeably - in a simple word, NO! Why, you might ask - because of spec changes from 1952 to 1954, the .308 lost a tiny bit of headspace room… plus the case walls are thinner than the 7.62’s. That means that the case may stretch when fired in the ever-so-slightly larger military chamber and lead to the possibility of a case rupture. 

History of 7.62x51 and .308

The history of 7.62x51 and .308 caliber cartridges is closely intertwined, as they essentially refer to the same cartridge with different names. The story begins with the development of the 7.62x51 cartridge in the 1950s for the M14 rifle, which was intended to replace the M1 Garand as the standard-issue rifle for the United States military.

The 7.62x51 cartridge quickly gained popularity due to its excellent accuracy and long-range capabilities. It was widely adopted by NATO countries and became the standard rifle cartridge for many military forces around the world.

In the civilian market, the .308 Winchester gained a strong following due to its performance and versatility. As semi-automatic rifles based on the AR-10 design became popular, manufacturers began chambering them specifically for the .308 Winchester cartridge. These rifles, often referred to as "308 ARs," are optimized for the .308 Winchester cartridge, with slight differences in dimensions and specifications to ensure reliable and accurate performance.

Today, both the 7.62x51 and .308 caliber cartridges continue to be widely used in military, law enforcement, and civilian applications. Their history is a testament to their reliability, versatility, and enduring popularity among shooters of all kinds.

So, whether you're a military veteran, a law enforcement officer, or a civilian shooter, understanding the history of the 7.62x51 and .308 cartridges can help you appreciate their lineage and choose the right ammunition for your AR-10 firearm.

Ballistics Comparison Between 7.62x51 and .308

If you're a gun enthusiast, you probably already know that ballistics are a crucial aspect to consider when selecting ammunition for your firearm. So let's dive into the ballistics comparison between 7.62x51 and .308 caliber cartridges, and see how they stack up against each other.

Both the 7.62x51 and .308 cartridges have similar ballistics characteristics due to their nearly identical dimensions. They both have a bullet diameter of .308 inches, and the overall length of the cartridges is also very close. This means that the external ballistics, such as trajectory and wind drift, will be virtually indistinguishable between the two.

When it comes to internal ballistics, such as chamber pressure and velocity, there might be some slight differences. The 7.62x51 cartridge was originally designed for military use and can handle higher chamber pressures. On the other hand, the .308 Winchester cartridge is loaded to slightly lower pressures to ensure reliable performance in civilian firearms. This could result in slightly higher muzzle velocities for the 7.62x51 cartridge compared to the .308 Winchester.

In summary, the 7.62x51 and .308 cartridges are incredibly versatile and have a range of applications. Whether you're a precision shooter, hunter, or just looking for a reliable self-defense firearm, the 7.62x51 and .308 cartridges will deliver the performance and reliability you need. Just choose the right barrel. So load up your rifle with these powerful cartridges and get ready to hit your target with confidence!