The Benefits and Limitations of 300 Blackout thumbnail image

The Benefits and Limitations of 300 Blackout

5D Tactical - 15th Jun 2023

AR-15 80 lower builders have several calibers to choose from. The 300 Blackout is a popular option, second only to the .223 Remington or 5.56 NATO. What is the reason behind the 300 BLK receiving a significant amount of attention?

With professional shooters regularly demonstrating its efficacy, there has been increasing interest in this caliber of ammunition. To become proficient with this high-quality firearm for shooting practice, we must first understand its pros and cons. This knowledge is essential.

Fortunately, at 5D Tactical, we proudly represent decades of expertise in the industry. This article breaks down the advantages and disadvantages of 300 Blackout ammunition. This information will help you make informed decisions when building your arsenal.


We’ll start by breaking down the caliber’s name .300 AAC Blackout.

The .300 is also known as 7.62x35mm. You can see in the photos above and below how much stouter of a round it is compared to .223 Remington or 5.56 NATO.

Advanced Armament Company (AAC) originally designed this round. However, AAC is often omitted from the name.

.300 BLK’s predecessor comes from the .300 Whisper, which was specifically designed to be shot while suppressed. The Whisper and the Blackout differ from each other.

.300 BLK projectiles

300 Blackout Projectiles. Photo Credit: Gun Digest


These calibers differ in the same way that the .223 differs from 5.56: in the neck diameter of their cartridge.

With the right ammunition, it is possible to fire a .300 Whisper out of a .300 BLK rifle. Here are some other common caliber comparisons:Hornady .300 Whisper

Photo Credit: Gun Digest

300 BLACKOUT VS 5.56

  • .300 blk ammo are bigger rounds than 5.56; in terms of ballistics, it packs a much bigger punch on impact.
  • 5.56 shoots flatter and flies at higher velocities, while costing half the price of .300.
  • Additionally, 5.56 tends to break apart more easily, minimizing the risk of over-penetration, especially compared to .300 BLK. 

    300 Blk Ballistic Trajectory

Photo Credit: Shooters Calculator

300 BLACKOUT VS .308

  • The AR15 platform is commonly used with .300 Blackout, whereas AR-10 style rifles are frequently paired with .308.
  • Blackout was designed to provide more energy and penetrate barriers better than 9mm while being compatible with a standard AR-15 magazine.
  • The .308 is a larger round, providing more energy and penetration than the .223/5.56 round. It has a longer range than .300.

300 BLACKOUT VS .223

  • Similar to 5.56, .223 requires almost double the barrel length to fully burn powder.
  • Additionally, it also requires more powder than .300 BLK.
  • That being said, 300 BLK's bullet drop increases much more than .223 past the 300-yard mark.

    .223 Ballistics Chart and Coefficient

Photo Credit: Gun Data


Without further ado, let's delve into the advantages that make the .300 BLK impressive. This specific caliber has great terminal ballistics.

What does that mean? It's the area of study also known as wound ballistics which examines the behavior of projectiles when impacting with a target. It also observes the transfer of energy during penetration.

We can assess the level of impact effectiveness of a bullet when it collides with a target. This is done by analyzing its structure and velocity. If you are searching for a highly effective caliber in close-quarters combat, the .300 BLK is the right choice for you.


So why is 300 BLK so effective for CQB?

Soldier with CQB 300 BLK setup

Photo Credit: Shutterstock - Suney Munintrangkul

Part of what makes the .300 BLK so optimal is its ability to fully burn the round's powder when being fired out of a short barrel. With just a 9-inch barrel, the 300 BLK is capable of performing at its max efficiency.

By contrast, .223 and 5.56 require nearly twice the length, if not more, to achieve the same result. This is why .300 BLK PDW (personal defense weapon) configurations are frequently utilized by SWAT teams.

With regard to accuracy - another benefit of 300 Blk is that it has the ability to reliably hit any target under 300 yards.


If a weapon has a shorter barrel, its total length remains controllable, even when a suppressor is added. Suppressors are especially nice to have if you are shooting indoors.

Paired with subsonic rounds and a suppressor, this combination reduces the recoil on a .300 BLK rifle almost to nothing with significantly less sound. That may be why more SWAT and SRT units across the country have begun to use this caliber in their rifles.

For civilians, particularly those concerned with home defense, it's a convenient alteration as you only need to exchange the barrel. Though, if you’re like us it’s really just a good excuse to build out a new complete upper.

If you already reload your own ammo it’s easy to start doing so for .300 BLK since the process of preparing brass for .300 BLK is the same as .223/5.56. All you need are new dies to accommodate the cartridge’s size.


Perhaps the best part of reloading .300 is that it uses less powder than .223 does which provides some savings in that aspect. If you don't have enough brass, you can actually use 5.56 casings as well.

They can be trimmed them down to the correct size for .300 BLK — we'd treat that only as a sort of last-resort measure (because it can be a pain to do that).

In terms of application, the .300 BLK is a fantastic choice in hunting large game and there is a wide range of projectile choices. Granted, a lot of hunting is about shot placement and you can hunt just about anything with 5.56.

.300 BLK might come in extra handy if you’re trying to wipe out a horde of feral hogs.

As we mentioned briefly above, part of the huge appeal of .300 BLK is its ability to utilize short barrel lengths. If your hunt is going to be long and involves a lot of trekking, add a LAW Folder and you could literally have a backpack gun less than 14″ while folded.

What's the best barrel length for 300 blk?

If you're on the market for a new 300blk AR-15 you'll see that there are barrel lengths 7.5" all the way up to 16 inches. 7.5" is a little short even for us so we like to play it safe.

Anything between 8 to 10.5" is what we'd choose so that if we added a suppressor, the build wouldn't be too long since most cans are about 6 inches in length.

Just remember that with any builds that have barrels shorter than 16" you'll have to consider if you're planning on going the 300 blk pistol or 300 blk sbr route (pistol meaning you attach a pistol brace and SBR meaning it involves a tax stamp).10.5 inch Complete Upper 300 BLK

Photo Credit: 5D Tactical


Honestly, there aren’t a whole lot of cons here but these are some factors you may want to consider:


If you’re looking to shoot distances past 300 yards, 5.56 is going to be the better option as it shoots a lot flatter because it flies at a higher velocity.

It’s not to say that you can’t hit targets at distances further than 300 yards but that it can progressively become more difficult once you factor in weather. With .300 BLK there is a massive bullet drop rate of 12” once you start aiming at targets at the 300-yard mark.


While it used to be cheaper, currently the cost of .300 BLK can be up to twice the amount of 5.56, making it a challenging purchase due to the ongoing COVID pricing.

If you have a reloading setup, it may reduce some of the expenses. This is only possible if you can buy all of the required components at a reasonable price.


While the .300 BLK is great for CQB, it actually might not be the best option for everyone's home defense due to its penetration ability. If you miss your target, there’s a good chance that the bullet will pass through multiple walls before fully stopping.

Over-penetration is a serious factor that people should consider if they live in a small home or apartment. Whereas, some 5.56 bullets break apart more easily and have less tendency to penetrate barriers like .300.


300 AAC Blackout is a strong and reliable round for the right situation. On CQB ranges, for example, you’ll be able to maximize force at short range.

Meanwhile, those who load their own ammunition will be happy to get more power with less powder. Now that you’re informed about its benefits and limitations, you’re empowered to build the weapon of your dreams.

To construct a new 80 percent 300 blackout rifle, consider our new complete upper kits. For additional information on .300 BLK ammo, feel free to contact our team.