.300 Blackout vs. 556

What's the Difference?

The .300 Blackout and 5.56mm (.556) are both popular rifle cartridges used in firearms. While they may appear similar, there are some notable differences between the two. The .300 Blackout is known for its versatility, as it can be used in both supersonic and subsonic loads, making it suitable for both short-range and long-range shooting. It also offers better performance in terms of energy and stopping power compared to the 5.56mm. On the other hand, the 5.56mm is widely used by military and law enforcement agencies due to its lightweight nature, high velocity, and flat trajectory. It is known for its accuracy and effective range, making it a preferred choice for medium to long-range engagements. Ultimately, the choice between the two depends on the specific requirements and preferences of the shooter.


Attribute.300 Blackout556
Caliber.300 Blackout5.56
Bullet Diameter.308 inches.224 inches
Effective Range300 meters600 meters
Maximum Range1,800 meters3,600 meters
Magazine CompatibilityCompatible with standard AR-15 magazinesCompatible with standard AR-15 magazines
Ballistic PerformanceDesigned for short-barreled rifles and offers better performance in close quartersDesigned for longer-range engagements and offers flatter trajectory
Suppressed PerformanceWorks well with suppressors due to subsonic loadsCan be used with suppressors, but supersonic loads may cause a sonic boom
AvailabilityLess common and more expensive compared to 5.56More common and generally less expensive

Further Detail


When it comes to choosing the right ammunition for your firearm, there are several factors to consider. Two popular options for rifles are the .300 Blackout and the 5.56. Both cartridges have their own unique attributes that make them suitable for different purposes. In this article, we will explore the characteristics of each round, including their ballistics, versatility, availability, and compatibility.


The .300 Blackout, also known as the 7.62x35mm, was specifically designed to offer improved ballistics over the 5.56 round in certain scenarios. It excels in short-barreled rifles and suppressor use. The .300 Blackout typically fires heavier bullets, ranging from 110 to 220 grains, compared to the 5.56's standard 55 to 77-grain projectiles. This heavier bullet weight allows for better energy retention and penetration, making it more effective for hunting or self-defense purposes.

On the other hand, the 5.56, or the .223 Remington, is a high-velocity round that offers flatter trajectory and better long-range performance. It is commonly used by military and law enforcement agencies due to its accuracy and ability to engage targets at extended distances. The 5.56 round is known for its fragmentation upon impact, causing significant tissue damage, making it a preferred choice for combat situations.


One of the significant advantages of the .300 Blackout is its versatility. It can be fired through both supersonic and subsonic loads, allowing shooters to choose between different velocities depending on their specific needs. Subsonic loads are ideal for suppressed firearms, reducing the noise signature significantly. Additionally, the .300 Blackout can use the same magazines and bolt carrier groups as the 5.56, making it easy to convert an existing AR-15 platform to shoot .300 Blackout rounds.

While the .300 Blackout offers versatility in terms of ammunition choices, the 5.56 is known for its versatility in terms of firearm platforms. The 5.56 round is widely used in various rifles, including the popular AR-15 platform. Its compatibility with a wide range of firearms and its availability in surplus quantities make it a preferred choice for many shooters. The 5.56 round also benefits from a vast selection of bullet types, including armor-piercing, tracer, and hollow point rounds, catering to different shooting needs.


When it comes to availability, the 5.56 has a clear advantage. It is one of the most widely produced and available rounds in the world. Its military adoption and widespread civilian use have led to a surplus of ammunition, making it easily accessible and affordable. This availability also extends to reloading components, allowing shooters to reload their own ammunition and tailor it to their specific needs.

On the other hand, the .300 Blackout, while gaining popularity, is not as readily available as the 5.56. It is a relatively newer cartridge and has a smaller market presence. However, as its popularity continues to grow, more manufacturers are producing .300 Blackout ammunition, making it increasingly accessible to shooters. Reloading components for the .300 Blackout are also available, allowing shooters to reload their own rounds and overcome any potential scarcity.


Compatibility is an essential factor to consider when choosing between the .300 Blackout and the 5.56. The 5.56 round is designed to be fired from rifles chambered in .223 Remington, while the .300 Blackout is designed to be fired from rifles chambered in .300 Blackout. However, the .300 Blackout can be fired from a rifle chambered in 5.56 by simply swapping the barrel. This interchangeability allows shooters to have a single firearm that can shoot both rounds, providing flexibility in ammunition choices.

It is important to note that while the .300 Blackout can be fired from a 5.56 chambered rifle, the reverse is not true. Firing a 5.56 round from a .300 Blackout chambered rifle can lead to dangerous malfunctions and potentially catastrophic failures. Therefore, shooters must ensure they have the correct chambering for the ammunition they intend to use.


Both the .300 Blackout and the 5.56 have their own unique attributes that make them suitable for different purposes. The .300 Blackout offers improved ballistics, versatility in ammunition choices, and compatibility with existing AR-15 platforms. On the other hand, the 5.56 provides excellent long-range performance, versatility in firearm platforms, and widespread availability. Ultimately, the choice between these two rounds depends on the shooter's specific needs, whether it be for hunting, self-defense, or military applications.

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