Understanding the Players
7.62x51mm NATO
The 7.62x51mm NATO is a military cartridge designed and standardized by the North Atlantic Treaty Organization. Its development emerged in response to the need for a versatile round that could be used in various military platforms, including rifles, machine guns, and sniper rifles. Its design emphasizes reliability, interchangeability, and suitability for global deployment across diverse climates and environments. This cartridge, created by the collaborative efforts of several countries, quickly gained widespread adoption due to its balance of power and manageable recoil.
.308 Winchester
The .308 Winchester, on the other hand, is a civilian cartridge, developed by Winchester in the mid-twentieth century. It was designed with hunting and civilian target shooting in mind. It is essentially the commercial equivalent of the 7.62x51mm NATO, sharing nearly identical dimensions and a similar performance profile. The .308 Winchester has become immensely popular among hunters across the globe due to its effective range and suitability for a wide array of game animals. It is also favored by competitive target shooters for its accuracy and relatively mild recoil.
Though often mistaken as exact duplicates, there are some distinctions. The most significant is the pressure specification. Military ammunition, like the 7.62x51mm, generally operates at a slightly lower pressure than commercial ammunition such as .308 Winchester. This difference means it’s generally safe to fire 7.62x51mm ammunition in a firearm chambered for .308 Winchester, though not always recommended to do the reverse, especially with older firearms, as the higher pressures of the .308 can, over time, cause damage to the rifle. Always consult your firearm’s manual for recommended ammunition.
Dissecting External Ballistics
Muzzle Velocity
Muzzle velocity is a critical starting point. It’s the speed at which the bullet exits the barrel. The .308 Winchester and 7.62x51mm NATO generally share comparable muzzle velocities when using bullets of similar weight. Bullet weight plays a major role in this, as heavier bullets will have slower muzzle velocities. For example, a .308 Winchester with a 150-grain bullet might leave the muzzle at around 2,800 feet per second (FPS), while a 180-grain bullet could be around 2,600 FPS. The 7.62x51mm NATO will typically exhibit similar numbers given similar loads. Some specific military loads, like those for designated sniper rifles, might be pushed to higher velocities, but on average, they are quite comparable. Differences in powder types, bullet design, and the specific manufacturing processes can subtly influence muzzle velocity, even when using cartridges of identical specifications. The specific rifle barrel length will also impact muzzle velocity; longer barrels generally permit higher velocities than shorter barrels.
Trajectory
Trajectory describes the path the bullet takes through the air. Due to gravity, all bullets experience a downward pull, resulting in a curved flight path. The .308 Winchester and 7.62x51mm NATO have similar trajectories, and this means that at the same distances and the same bullet weight, the bullets will fall about the same amount. The trajectory of the bullet is influenced by a number of factors, but the most important are bullet weight, muzzle velocity, and ballistic coefficient. Lighter, faster bullets will have flatter trajectories, which is better. Heavier, slower bullets will experience greater bullet drop over the same distance. It’s important to account for this when aiming at a target at distance, especially when using a scope.
Effective Range
Effective range is another vital aspect. It refers to the distance at which a rifle and its ammunition can consistently achieve accurate shots on target. The effective range of both cartridges can vary based on the specific load used, the rifle’s accuracy, and the shooter’s skill. However, generally, both cartridges have effective ranges that extend well beyond five hundred yards for hunting and precision shooting. The term “effective range” means the distance at which the shooter can consistently hit the target with reasonable accuracy. The maximum effective range of any cartridge is the distance where the bullet’s energy is depleted to an extent that it may no longer be reliable at performing the desired task, such as taking down an animal.
Ballistic Coefficient (BC)
Ballistic coefficient (BC) is another crucial element. It is a measure of a bullet’s ability to overcome air resistance. A higher BC means the bullet is more aerodynamic and will experience less drag, resulting in less bullet drop, greater retained velocity, and improved resistance to wind drift. A bullet with a higher BC will tend to have a flatter trajectory and retain more energy over distance. The 7.62x51mm NATO and .308 Winchester have a range of ballistic coefficients dependent on the bullet design and weight. The best long-range performance is generally achieved with bullets that have a higher BC.
Wind Drift
Wind drift refers to the horizontal movement of a bullet caused by crosswinds. Wind is a significant factor that any marksman must take into account. Both the 7.62x51mm NATO and .308 Winchester are affected by wind drift, but the extent of the drift is influenced by the wind speed, the bullet’s BC, and the distance to the target. Long-range shooters are well aware of the importance of judging wind conditions accurately because even a slight crosswind can move a bullet significantly at extreme ranges.
Energy at Different Ranges
Lastly, it’s important to consider the retained energy at various ranges. A bullet slows down over distance as it loses energy. The retained energy determines the bullet’s ability to penetrate, expand, and effectively deliver its energy to the target. While the initial energy at the muzzle will be comparable between the two rounds given similar loads, factors such as bullet weight and ballistic coefficient play a role in determining how much energy is retained at longer distances. Generally, for hunting purposes, the .308 Winchester and the 7.62x51mm NATO both possess enough energy at several hundred yards to humanely harvest medium and large game.
Examining Terminal Ballistics
Energy on Impact
Energy on impact is one of the most important factors. It determines the amount of energy transferred from the bullet to the target upon impact. The energy of the bullet on impact is directly related to the bullet’s velocity and weight. For hunting, the ability to deliver sufficient energy on impact is crucial for achieving a quick and humane kill. The .308 Winchester and 7.62x51mm NATO, with their respective bullet weights and velocities, generally deliver enough energy on impact to reliably take down many common game animals at reasonable ranges.
Penetration
Penetration is the bullet’s ability to pierce through the target. Proper penetration is vital for reaching vital organs and ensuring a decisive and ethical kill. The .308 Winchester and 7.62x51mm NATO are known for their penetration capabilities, and these abilities depend on bullet design and construction. Some bullets are designed for controlled expansion, where the bullet expands to increase its diameter, causing more damage, and then limits penetration. Others are designed to penetrate, such as those used by the military.
Wound Characteristics
Wound characteristics refer to the nature of the injury the bullet creates. This is affected by various factors, including bullet type, velocity, and impact angle. The .308 Winchester and 7.62x51mm NATO produce wounds that are similar, though a bullet’s design impacts the size and shape of the wound. Expanding bullets typically create larger wound cavities than full metal jacket bullets, as they deliver more energy to the target and cause a more significant disruption of tissue.
Bullet Expansion and Fragmentation
Bullet expansion and fragmentation are also important features. Expansion occurs when a bullet increases in diameter upon impact with the target. Fragmentation involves the bullet breaking apart into multiple pieces. These processes, if the bullet is designed to do so, increase the energy transfer, damage, and the chances for a rapid incapacitation of the target. The .308 Winchester and 7.62x51mm NATO offer a diverse selection of bullets that can be used for either terminal ballistics, depending on the needs of the shooter.
Choosing the Right Tool
Weapon Availability and Cost
When deciding between the .308 Winchester and the 7.62x51mm NATO, several considerations come into play. Weapon availability and cost are relevant. Both cartridges are incredibly popular, resulting in an abundance of rifles chambered for each. The cost of the rifle can vary, depending on the manufacturer, features, and intended application.
Ammo Availability and Cost
Ammunition availability and cost are also factors to consider. Both cartridges are produced in substantial quantities, and they can be found in most gun stores, both in your local store and online. The cost of the ammo varies greatly depending on factors such as the bullet weight, the bullet’s construction, and the brand. Military surplus ammunition is often available for the 7.62x51mm NATO, which can provide an economical option for target practice.
Intended Use
The intended use should be the guiding principle. For hunting, both cartridges excel at taking down medium to large game. The .308 Winchester often is the go-to choice for hunters because it has a wide variety of bullet types that are designed to meet different hunting needs. For target shooting, both cartridges offer great performance. The .308 Winchester tends to be preferred by many target shooters due to its enhanced availability, bullet options, and its reputation for accuracy. For self-defense, military, or law enforcement applications, the 7.62x51mm NATO is used for its proven reliability and the ability to deliver a large amount of energy. However, the .308 Winchester is not uncommon in this role as well.
In Conclusion
The *7.62 vs .308 ballistics* reveal that these cartridges are remarkably similar in their performance. They share comparable muzzle velocities, trajectories, effective ranges, and energy profiles. Both are effective rounds. The differences, in reality, are minor. The choice between them often comes down to individual preferences, firearm availability, ammunition availability, and the specific application. Consider the intended use, the desired bullet performance, and the availability of ammunition to make the best choice for your needs. Whether you choose the 7.62x51mm NATO or the .308 Winchester, you’re choosing a round with a proven track record for versatility, accuracy, and stopping power.
