Understanding the Fundamentals
Before we delve into the specifics, it’s important to understand what we’re dealing with. The .308 Winchester, also known as the 7.62x51mm NATO, is a powerful and versatile cartridge with a long and distinguished history. It’s known for its impressive stopping power and long-range capabilities, making it a favorite among hunters and marksmen.
The 5.56x45mm NATO is a smaller, lighter cartridge, often associated with the AR-15 platform. It gained prominence during the Vietnam War and has since become the standard rifle cartridge for many military forces worldwide. Its appeal lies in its relatively low recoil, high rate of fire, and affordability.
Both rounds represent a significant piece of firearms history and understanding their differences and similarities is crucial to making an informed decision.
The Science of Ballistics: Examining the Flight of the Bullet
Ballistics, the study of projectiles in motion, provides the foundation for understanding how these two cartridges perform. Let’s examine the key aspects of ballistics and how they differentiate the .308 from the 5.56.
Mapping the Path of the Bullet: Trajectory
Trajectory refers to the curved path a bullet takes as it travels through the air. Gravity constantly pulls the bullet downward, and its initial velocity and shape determine how far it will travel before it drops significantly. A flatter trajectory means the bullet drops less over a given distance, making aiming easier, especially at longer ranges.
The .308, with its heavier bullet and higher ballistic coefficient (ability to resist air resistance), tends to have a flatter trajectory over longer distances compared to the 5.56. This means that for long-range engagements, you’ll need to compensate for the drop of a 5.56 round more significantly.
Unleashing the Speed: Muzzle Velocity
Muzzle velocity is the speed at which the bullet leaves the barrel of the firearm. This is a critical factor in determining the bullet’s energy and its ability to reach the target quickly. Generally, the .308 has a lower muzzle velocity than the 5.56, although the exact numbers depend on the specific load (bullet weight, powder type, etc.). The higher muzzle velocity of the 5.56 allows it to reach its effective range in a short period.
Calculating Impact: Energy
Kinetic energy is the energy a bullet possesses due to its motion. It’s a crucial factor in terminal performance. Energy is measured in foot-pounds (ft-lbs), and it increases with both the mass of the bullet and its velocity. The .308, because of its heavier bullet and potentially higher velocity at shorter distances, typically has significantly more kinetic energy than the 5.56, especially at longer ranges. This translates to a greater potential for stopping power and penetration.
Defying the Elements: Wind Drift
Wind drift is the effect of wind pushing a bullet off course. Wind can significantly impact accuracy, especially at longer ranges. The .308, due to its higher sectional density and often superior ballistic coefficient, is less susceptible to wind drift than the lighter, faster 5.56. This makes the .308 a better choice in windy conditions or for precision shooting at distances where wind plays a major role.
Terminal Performance: What Happens When It Hits
The impact of a bullet on a target is the ultimate measure of its effectiveness. Terminal performance encompasses everything that happens from the moment the bullet strikes the target.
Creating the Wound: Wound Cavity
When a bullet strikes a target, it creates a wound cavity. There are two types: the temporary cavity, which is a result of the bullet’s passage and the energy it imparts, and the permanent cavity, which is the actual hole left by the bullet. Generally, the .308, with its higher energy and heavier bullet, is capable of creating a larger and more devastating temporary and permanent wound cavity.
Conquering Obstacles: Penetration
Penetration is the ability of a bullet to pass through barriers. A bullet’s penetration capabilities depend on factors like its mass, velocity, and construction. The .308 generally has superior penetration capabilities compared to the 5.56. This is because its heavier bullet carries more momentum. This is especially significant when encountering barriers like car doors, walls, or heavy brush.
Expanding or Fragmentation: Bullet Deformation
Bullet construction plays a critical role in terminal performance. Some bullets are designed to expand upon impact, increasing their diameter and transferring more energy to the target. Others fragment, breaking apart into smaller pieces. The specific effects of expansion or fragmentation depend on the bullet design and the target. While there’s no single answer as to which is “better,” a heavier bullet offers increased momentum which is transferred when impact is made with the target.
The Advantages of the .308
The .308 has several inherent advantages that make it a strong contender in many scenarios:
Power in Every Shot
.308 rounds deliver a substantial amount of kinetic energy at most ranges, giving it an edge when it comes to stopping power and the ability to neutralize threats effectively. This is particularly beneficial in situations where immediate incapacitation is crucial.
Punching Through Barriers
The .308’s ability to penetrate barriers is a significant advantage in tactical or self-defense scenarios. It’s more likely to defeat obstacles like car doors or walls, increasing its effectiveness in diverse environments.
Dominating the Distance
The .308 performs exceptionally well at long ranges. Its flatter trajectory, resistance to wind drift, and retained energy make it a superior choice for precision shooting and hunting at extended distances.
Harnessing the Weight: The Variety of Bullets
The .308 offers a broad selection of bullet weights. This allows for customization to suit various purposes. Heavier bullets are often preferred for hunting larger game due to their increased penetration and energy transfer.
The Advantages of the 5.56
The 5.56 boasts its own set of advantages:
Smooth Handling
The 5.56 typically produces less recoil than the .308. This allows for faster follow-up shots and helps shooters maintain better control of the weapon, especially during rapid firing.
Volume of Fire
Due to its lighter weight and smaller size, soldiers and civilians can carry more 5.56 ammunition for the same weight.
Easy to Carry
The .308 round can often be significantly heavier per cartridge than a 5.56, meaning that even the same amount of ammo will feel much different.
Affordable Shooting
The 5.56 is generally cheaper than the .308.
Rifle Variety
The 5.56 has more rifle platforms than the .308, making for more options when selecting a rifle.
Common Applications and the Firearms that Use Them
Both .308 and 5.56 are used in a variety of applications.
The .308 in Action
- Hunting: Perfect for medium and large game.
- Long Range Shooting: Built for precise target shooting.
- Military & Law Enforcement: Used in designated marksman rifles.
The 5.56 at Play
- Self Defense: Easy to handle and use.
- Hunting (Smaller Game): Well suited for light game.
- Military & Law Enforcement: Popular platform for patrol.
Firearms of Note
- .308: AR-10, many bolt-action rifles, and battle rifles are common chamberings.
- 5.56: AR-15 is a staple, but other platforms exist.
Weighing Your Options: Making the Right Choice
Choosing between .308 and 5.56 requires careful consideration.
Your Intended Purpose
The intended use will impact what round you select.
Distance and Targets
Knowing the range and targets is key for choosing a caliber.
Considering Personal Choices
Your comfort with the recoil, budget, and other factors need to be factored in.
Final Thoughts
The .308 and the 5.56 are both excellent cartridges. .308 excels when power and range are paramount. The 5.56 is ideal when maneuverability, affordability, and high capacity are priorities. The “best” choice always comes down to the user’s individual needs and preferences. Consider your intended use, the typical ranges you’ll be shooting at, and your tolerance for recoil.
Ultimately, the .308 and the 5.56 represent a long-standing debate within the firearms world. By understanding the strengths and weaknesses of each, you can make an informed decision that aligns perfectly with your needs. Choose wisely, and enjoy your time at the range!
