Comparing the Big Three: .223/5.56, .300 Blackout, and .308 Winchester

The .300 Blackout and .308 Winchester cartridges are popular for sporting rifles, home defense and hunting. Both cartridges offer excellent velocities and energy transfer, although their terminal ballistics differ depending on the ammunition used. While the .300 Blackout might be slightly better for CQB (close-quarters battle) applications due to its shorter barrel length, the .308 Winchester offers better long-range accuracy, making it an excellent choice for shooting competitions and big game hunting. 

When deciding between the two cartridges, it’s important to consider the type of bullet you’ll use, what type of rifle you have or plan to purchase, and how far away your targets are likely to be. Ammunition companies offer a wide selection of bullets designed specifically for each cartridge, so make sure you check out all your options before choosing one over the other.

How Do We Categorize Cartridges?

The Imperial System of Measurement and the Metric System are two commonly used systems today. Cartridge measurements are prescribed according to both systems but are frequently referred to by their diameter in either inches or millimeters. The 5.56x45mm NATO cartridge has a diameter of 5.56mm and a length of 45mm, whereas its counterpart, the .223 Remington, has a diameter of 0.308 inches (7.8 millimeters). It is important to note that although their measurements might be similar, these cartridges must not be interchanged as this could lead to dangerous consequences due to incompatibility issues associated with them. Safety should always come first when handling ammunition which is why it is advised not to use 5.56mm ammunition in a .223 rifle.

Not All Bullet Cartridges Are Interchangeable

I want to point out a fundamental but often overlooked problem: never use bullets in rifles with different calibers that aren’t designed for the bullet.

The .308 Winchester is better for long-range shooting, while the .300 AAC Blackout is better for close-quarters shooting. They’re two different chambers and rifles.

.300 AAC Blackout is a 7.62x35mm bullet developed with the AR short-action platform. The .300 BLK cartridge is similar in size to the popular .223/5.56 caliber. Still, it is extremely dangerous to use a .300 BLK round in a .223/5.56 chamber. The risk of damaging your rifle or injuring yourself is more significant when the bullet is larger than the bore.

The .308 Win is the same as the military 7.62×51mm NATO cartridges. However, the only 7.62×51mm NATO cartridge you can use in a .308 Winchester rifle is the one that is designed for it. Using anything else is ill-advised.

7.62x51mm rounds can be used in .308 Winchester rifles, but not the other way around. Be sure to always label and organize your ammunition crates.

Who Has the Best? 308 Winchester against 300 Blackout and 223/5.56

The 5.56x45mm NATO, the.300 Blackout, and the.308 Winchester are all cartridges that function well in various situations, according to the majority of those who like shooting and hunting. Even though the 5.56, 300 Blackout, and 308 Winchester share some capabilities, you should be aware of some significant differences between them.

The cartridges depict three various modes of thought, with the .223/5.56 being smaller and lighter, the .308 being more prominent and heavier, and the .300 Blackout being a compromise. This is why cartridges with dedicated followings need more clarification about their capabilities. The debate about which caliber is better between the 5.56, 300 Blackout, and 308 Winchester can take time to understand.

Although the .223 Remington and the 5.56x45mm NATO are different cartridges, the practical difference in performance between them is minimal. The .223 uses a different caliber bullet, and the .308 has an entirely different case design “Be careful if you try to switch out the.223 Remington or.308 Winchester for their NATO cousins. The .223 uses a different caliber bullet, and the .308 has a different case design.”

History: 5.56 vs. 300 Blackout vs. 308 Winchester

After much consideration, the M-14 was developed after World War II. American military leaders wanted to replace the M-1 Garand rifle and the .30-06 Springfield cartridge. After much consideration, they created the M-14. They specifically sought out a rifle. That could fire fully automatically and had a detachable magazine, similar to the German StG-44 or the Soviet AK-47. After using the M-1 Garand for some time, the Army switched to the M-14 rifle designed to fire the new 7.62x51mm NATO cartridge.

The 7.62x51mm NATO M80 ball load was designed as an improvement over the existing .30-06 cartridge in terms of the shorter case, higher muzzle velocity and improved powder technology. As a result, the 147-grain bullet of the smaller 7.62x51mm round had equivalent ballistic performance to that of the larger .30-06 Springfield cartridge, despite having a shortened case length of 51 millimeters compared to 63 millimeters of the latter. Additionally, this new design provided impressive muzzle velocity numbers at 2,750 feet per second and a 2,469 foot-pounds energy rating. This caliber achieved notable penetration capability against body armor and other materials without sacrificing accuracy at longer ranges – making it a practical choice for various militaries across the globe.

Which Cartridge Should You Be Hunting With?

While the 7.62x51mm cartridge had commercial potential, Winchester introduced the .308 Winchester cartridge for the civilian hunting and shooting markets.

The .308 Winchester was popular among American hunters and shooters because it was efficient, powerful, and accurate. The same characteristics that soldiers and leaders in the American military appreciated in the 7.62x51mm earned it widespread approval for its performance in designated marksman/sniper rifles and machine guns.

The M-14 rifle was a powerful weapon, but its high cost and multiple variants caused many to balk at its price. Additionally, the need for its maintenance was an issue for many military officials. As a result, the M-16 rifle with a 5.56x45mm cartridge was developed as an alternative, providing a more lightweight but still effective weapon within a more reasonable budget. This new development allowed military officials to have more flexibility in their use of firearms while also reducing prohibitive costs and maintenance time.

The 5.56x45mm M193 ball load was derived from the .223 Remington. It fired a .224″ 55-grain full metal jacket bullet at 3,250 feet per second (1,290-foot-pounds of energy).

The improved rifle and cartridge were adopted by the US Air Force, Army, and Marine Corps in the 1960s. The M-16 rifle and the 5.56x45mm cartridge became widely used during the Vietnam War. The rifle and cartridge had severe problems when first used in that conflict.

Following military operations, several soldiers and marines who used the M-16 in combat grumbled about the 5.56x45mm cartridge’s lackluster stopping power.

There were issues with the AR-15 rifles, larger caliber cartridges were developed in the 1990s and early 2000s to function with these rifles. The 6.8 Remington SPC, the.458 SOCOM, the 6.5 Grendel, and the.50 Beowulf.

Battle of the Big Bore AR Cartridges

The prominent military members were searching for a new cartridge type with similar physical dimensions and operating mechanism as the 5.56x45mm so that it could fit into the standard M16/AR magazine without any modifications. The desired chambering was .30 caliber so that the same bolt and gas system could be used in an M-16 or M-4 rifle. This meant that soldiers would not have to carry additional equipment or modify their weapons just to use different types of ammunition, which would provide them greater versatility on the battlefield.

The.300 Whisper cartridge proved to be the key to their discovery. The .300 Whisper was designed by JD Jones of SSK Industries in the 1990s. It uses a .221 Remington Fireball case necked up to shoot .30 caliber projectiles. However, the .300 Whisper was a wildcat cartridge, so designers at Advanced Armament Corporation (AAC) made a few modifications to it and got it approved by SAAMI as the .300 AAC Blackout. The design was able to be put into large-scale production by ammunition manufacturers.

The .300 BLK, also known as 7.62x35mm, is a popular and widely available rifle cartridge that can be loaded with a variety of different bullets. Hornady produces one of the most popular bullet loads for this cartridge – a 125-grain hollow point traveling at 2,175 feet per second, giving it an energy of 1,313 foot pounds. This ammo is ideal for hunting applications, where quietthe increased accuracy is important and maximum energy transfer to the target is desired. The 110-gram load is considered to be supersonic and can travel at 2,350 feet per second. Having multiple supersonic load options makes finding the perfect ammo for any situation simple and accessible.

Differences Between the .300 AAC Blackout and the .308 Winchester

The .300 AAC Blackout and the .308 Winchester only share the use of a .308 caliber bullet.

In other words, the .308 is a more powerful round than the .300.

That’s why it’s a hunting round, in contrast, to fast follow-up shooting via semi-auto AR-15s or M4 Carbines.

Knowing that the performance data comes from ballistic calculators that are trusted to understand the difference between them is essential.

Every time a bullet is shot, the results will be slightly different. Still, they will usually fall into average categories, which makes them reliable.

Computer-generated data is a useful tool when comparing different types of guns. By taking measurements such as velocity, kinetic energy, recoil, accuracy and stopping power into account, it is easy to analyze changes between weapons in an objective manner. However, this doesn’t mean one gun is definitively better than another – the.308 may have higher metrics in some areas, but the.300 will still be more suitable for certain applications due to other factors. For instance, the.300 is well-suited for lightweight firearms or home defense scenarios thanks to its automatic follow-up shot capability. This highlights the importance of using computer-generated data when making comparisons between different types of firearms but not relying exclusively on it for all evaluations.

Let’s start with recoil.

The.308 Win rifle is well suited for hunters, providing the perfect range and accuracy for most shooting needs. The recoil produced by the.308 round is much greater than that of the.300 BLK, which makes it more difficult to handle and results in more felt recoil by the shooter. Despite this, the.300 AAC Blackout has its uses; it is well suited for close-range applications where multiple shots would need to be taken very quickly. 

As well as the benefits of a high muzzle velocity and accuracy, it also produces less felt recoil than other rounds like the .300 Win Mag. All in all, rookies may have no trouble taking on a variety of hunting tasks with a .308 rifle in hand as long as they are willing to accept higher levels of felt recoil.

The .308 Has a Higher Velocity.

Velocity is related to accuracy, recoil, stopping power, and trajectory. It can identify unpredictable and out-of-control high-performance rounds and bullets with a higher risk of exploding.

If you know the velocity of a bullet, you have a pretty good idea of what the bullet will do.

At 500 yards, the .308 Winchester round has a velocity 500 fps higher than the .300 AAC Blackout round.

The .300 supersonic ammo has a velocity of around 1,125 fps on average. In contrast, subsonic ammo has a slightly lower velocity.

In other words, .308 bullets are more precise over long distances. 300 Blackout bullets are more versatile and work better for close range.

Captain Hunter is a seasoned hunting mentor with over 20 years of experience in the field. His passion began as a young man on trips with his father and grandfather in the Colorado mountains. Today, he shares his unmatched skills in survival, tracking, and marksmanship through his website When he's not volunteering with youth hunting programs, you can find Captain Hunter providing expert hunting tips, gear reviews, and answers to your most pressing questions. His decades of experience make him the trusted guide to help any outdoorsman master the sport.

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