What are the Differences Between 5.56x45mm vs .308 Winchester Ammo?

Historical Background

The development of the .556 and .308 cartridges has a rich history that dates back to the mid-20th century.

The .308 cartridge was developed in the 1950s as a hunting cartridge and was later adopted by the U.S. Military for use in the M14 rifle during the Vietnam War.

The .556 cartridge, on the other hand, was developed in the early 1960s as a replacement for the .308 cartridge in the M16 rifle.

The .308 cartridge was designed by Winchester Repeating Arms in 1952 and was based on the .300 Savage cartridge. It was initially called the .30-51, but it was later renamed the .308 Winchester.

The cartridge was designed for use in hunting rifles and was later adopted by the U.S. Military for use in the M14 rifle.

The .556 cartridge was developed by Eugene Stoner, Robert Fremont, and L. James Sullivan of the Fairchild ArmaLite Corporation in the early 1960s.

The cartridge was designed to be used in the ArmaLite AR-15 rifle, which later became the M16 rifle. The .556 cartridge was designed to be smaller and lighter than the .308 cartridge, which would allow soldiers to carry more ammunition.

During the Vietnam War, the U.S. Military used both the M14 rifle, which fired the .308 cartridge, and the M16 rifle, which fired the .556 cartridge.

The M14 rifle was a heavy and bulky weapon, while the M16 rifle was lightweight and easy to carry. The M16 rifle quickly became the preferred weapon of U.S. soldiers in Vietnam.

Today, the AR platform is one of the most popular rifles in the world, and it owes its success to the development of the .556 and .308 cartridges.

The AR-15 rifle is the civilian version of the M16 rifle, and it is widely used for hunting, target shooting, and self-defense. The AR-10 rifle, which fires the .308 cartridge, is also a popular choice for hunters and target shooters.

FN Herstal, a Belgian firearms manufacturer, is one of the largest suppliers of small arms to the U.S. Military. They produce the M240 machine gun, which fires the .308 cartridge, and it is widely used by the U.S. Army and other NATO countries.

The M240 is a versatile weapon that can be used for a variety of tasks, including infantry support, vehicle-mounted firepower, and base defense.

5.56 vs .308 Technical Specifications

Bullet Weights

When comparing .308 and 5.56 cartridges, one of the most significant differences is the bullet weight.

The .308 cartridge typically has a bullet weight between 150 and 180 grains, while the 5.56 cartridge has a lighter bullet weight of around 55 grains.

This difference in bullet weight affects the trajectory, accuracy, and stopping power of the round.

Case Length and Capacity

Another difference between the two cartridges is the case length and capacity. The .308 cartridge has a longer case length of 2.015 inches and a larger case capacity of 56.0 grains of water.

In contrast, the 5.56 cartridge has a shorter case length of 1.76 inches and a smaller case capacity of 28.5 grains of water.

This difference in case length and capacity affects the amount of powder that can be loaded into the cartridge, which in turn affects the velocity and energy of the bullet.

Barrel Length

The barrel length of a rifle also affects the performance of the cartridge. A longer barrel typically results in higher muzzle velocity and energy.

The .308 cartridge performs best with a barrel length of 20-24 inches, while the 5.56 cartridge performs best with a barrel length of 16-20 inches.

Muzzle Energy

Muzzle energy is the energy of the bullet as it leaves the barrel of the rifle. The .308 cartridge has a higher muzzle energy than the 5.56 cartridge due to its heavier bullet and larger case capacity.

The .308 cartridge typically has a muzzle energy of 2,500-3,000 foot-pounds, while the 5.56 cartridge has a muzzle energy of around 1,300 foot-pounds.

Chamber Pressure

Chamber pressure is the pressure generated by the burning powder inside the cartridge as it is fired. The .308 cartridge has a higher chamber pressure than the 5.56 cartridge due to its larger case capacity and heavier bullet.

The .308 cartridge typically has a chamber pressure of 62,000 PSI, while the 5.56 cartridge has a chamber pressure of around 55,000 PSI.

In summary, the .308 cartridge is a larger and heavier cartridge with a longer case length and larger case capacity, resulting in a higher muzzle energy and chamber pressure.

The 5.56 cartridge is a smaller and lighter cartridge with a shorter case length and smaller case capacity, resulting in a lower muzzle energy and chamber pressure.

When choosing between the two cartridges, it is important to consider the intended use and the specific rifle being used.

5.56 vs .308 Performance Analysis

Range

When it comes to range, the .308 Win has a clear advantage over the 5.56 NATO. The .308 is a larger, heavier round that is capable of traveling longer distances with greater accuracy. On the other hand, the 5.56 NATO is a lighter round with a shorter effective range.

Recoil

5.56mm: The 5.56mm NATO round is commonly used in rifles such as the AR-15 platform. It is known for its relatively mild recoil compared to larger calibers. Here’s a qualitative assessment of the recoil:

• Low to moderate recoil: The recoil is generally manageable and easily controllable, making it suitable for most shooters.
• Light push or sharp snap: The recoil impulse is often described as a quick, snappy jolt or a gentle push.

.308 Winchester (7.62x51mm NATO): The .308 Winchester is a larger caliber commonly used in rifles like the AR-10 or bolt-action rifles. It delivers significantly more energy than the 5.56mm, resulting in increased recoil. Here’s a qualitative assessment of the recoil:

• Moderate to heavy recoil: The recoil is noticeably stronger compared to the 5.56mm, requiring more effort to control, especially in lightweight firearms.
• Strong push or solid thump: The recoil impulse can be felt as a solid, forceful push or a thump against the shoulder.

Stopping Power

The .308 Win has a higher stopping power than the 5.56 NATO. It is a larger, heavier round that can take down larger game or incapacitate a target more effectively. However, the 5.56 NATO is still a potent round that can be effective in certain situations.

Effective Range

The effective range of a firearm is the distance at which it can reliably hit a target. The .308 Win has a longer effective range than the 5.56 NATO, making it a better choice for long-range shooting. However, the 5.56 NATO is still effective at shorter ranges.

Flatter Trajectory

Note: The values represent the bullet’s trajectory in inches above (+) or below (-) the line of sight at the specified distance. Negative values indicate the bullet is below the line of sight, while positive values indicate it is above the line of sight.

In general, the 5.56mm cartridge experiences a flatter trajectory compared to the .308 Winchester. This is due to factors such as the higher muzzle velocity and lighter weight of the 5.56mm bullet, which results in less bullet drop over distance. However, it’s important to consider that trajectory can be influenced by various factors, including barrel length, bullet weight, environmental conditions, and individual loadings, among others.

Ballistic Performance

The ballistic performance of a round refers to its ability to maintain velocity and accuracy over long distances. The .308 Win has superior ballistic performance compared to the 5.56 NATO, making it a better choice for long-range shooting.

Overall, the 308 vs 556 debate comes down to personal preference and the intended use of the firearm.

While the .308 Win has a clear advantage in terms of range, stopping power, and ballistic performance, the 5.56 NATO is still a potent round that can be effective in certain situations.

By understanding the differences between the two rounds, shooters can make an informed decision and have confidence in shooting their firearm.

5.56 vs .308 Usage Scenarios

When it comes to choosing between .556 and .308, it’s important to consider the usage scenarios. Here are some of the most common scenarios where these cartridges are used:

Hunting

For hunters, the choice between .556 and .308 largely depends on the type of game they are hunting. The .308 Winchester is a popular hunting round for big game hunting, while the .556 is better suited for smaller game.

When hunting situations require quick follow-up shots, the .556 is a great option due to its low recoil and high magazine capacity. However, for big game hunting, the .308 is the better option due to its powerful and accurate performance.

Home Defense

When it comes to home defense, both the .556 and .308 can be effective options. However, the .556 is generally considered to be a better choice due to its lower recoil, higher magazine capacity, and lighter weight.

In defensive situations, quick follow-up shots can be crucial, and the .556’s lower recoil allows for faster and more accurate shooting.

Target Shooting

For target shooting, both the .556 and .308 are popular choices. The .308 is a versatile cartridge that can be used in a variety of handguns, semi-automatic rifles, and bolt-action rifles.

It is a great choice for target practice and precision shooting due to its excellent accuracy and long-range capabilities. On the other hand, the .556 is a popular choice for tactical departments and rifle shooting tips due to its low recoil and high magazine capacity.

Competitions

When it comes to competitions, the choice between .556 and .308 largely depends on the type of competition. For target shooting competitions, the .308 is a popular choice due to its excellent accuracy and long-range capabilities.

However, for competitions that require quick follow-up shots, such as tactical competitions, the .556 is a better option due to its low recoil and high magazine capacity.

Overall, the choice between .556 and .308 largely depends on the specific usage scenario. Whether you’re a hunter, shooter, or competitor, it’s important to choose the cartridge that best fits your needs.

5.56 vs .308 Cost Analysis

When comparing the .308 and .556 cartridges, one factor that cannot be ignored is the cost. The cost of ammunition can vary greatly depending on the brand, type, and quantity purchased.

In general, the .308 cartridge is more expensive than the .556 cartridge. This is because the .308 uses a larger bullet and more powder, which requires more material to produce. As a result, the cost per round of .308 ammunition is typically higher than that of .556 ammunition.

However, it is important to note that the cost of ammunition is not the only cost involved in shooting. Reloading supplies, such as brass, bullets, and powder, can also add to the overall cost.

Reloading can be a cost-effective option for those who shoot frequently, as it allows for the reuse of brass and the ability to customize loads to specific needs. However, reloading requires an initial investment in equipment and supplies, which can be expensive.

In addition to the cost of ammunition and reloading supplies, there may be other costs involved in shooting, such as range fees, transportation costs, and equipment maintenance. It is important to take all of these costs into account when budgeting for shooting activities.

Overall, while the .308 cartridge may be more expensive than the .556 cartridge, there are other factors to consider when evaluating the cost of shooting.

By carefully considering all costs involved, shooters can make informed decisions about which cartridge is the best fit for their needs and budget.

Law Enforcement and Military Use for 5.56 vs .308 

When it comes to law enforcement and military use, both the .308 and .556 calibers have been widely adopted. The choice of caliber depends on the specific mission and the type of engagement the operator expects to face.

For military use, the .556 caliber is the standard NATO cartridge, also known as the 5.56x45mm NATO cartridge. It has been used by NATO allies since the 1980s and is favored for its light weight, high velocity, and low recoil. The .556 caliber is commonly used in rifles such as the M16 and M4.

Law enforcement agencies also commonly use the .556 caliber in their rifles. This is due to its accuracy and stopping power, which is important for situations where officers may need to engage targets at longer ranges.

However, some agencies also use the .308 caliber for certain situations, such as when a higher level of penetration is needed.

The .308 caliber, also known as the 7.62×51 NATO, is favored by some military units and law enforcement agencies for its longer range and higher stopping power.

It is commonly used in rifles such as the M14 and SR-25. The .308 caliber is also used for hunting and long-range shooting.

It is important to note that the .223 caliber is not the same as the 5.56x45mm NATO cartridge, and the .308 caliber is not the same as the 7.62×51 NATO.

While the two calibers may look similar, there are differences in chamber pressure and other factors that make them incompatible.

In summary, both the .556 and .308 calibers are widely used by law enforcement and military agencies. The choice of caliber depends on the specific mission and the type of engagement the operator expects to face.

5.56 vs .308 Reloading

Reloading ammunition is a great way to save money and customize your loads to your specific needs. Whether you are reloading .556 or .308, the process is similar.

Brass

When reloading, we recommend using high-quality brass. This will ensure consistent performance and longevity of your ammunition. We suggest using brass that has been fired only once, as this will reduce the likelihood of case head separation and other issues.

Bulk Ammo

If you are looking to reload in bulk, we suggest purchasing brass in bulk as well. This can save you a significant amount of money in the long run. However, it is important to ensure that the brass is of high quality and has been properly inspected before use.

Budget Reloading Supplies

Reloading can be an expensive hobby, but there are ways to save money on supplies. We suggest purchasing in bulk and looking for deals on reloading supplies. Additionally, you can save money by using less expensive powders and primers, as long as they are still of good quality.

Overall, reloading is a great way to save money and customize your loads to your specific needs. By using high-quality brass and other supplies, you can ensure consistent performance and longevity of your ammunition.