.300 Blackout rifle

Best .300 Blackout Barrels

Are you in the market for a new barrel for your AR-15 in .300 Blackout? If so, you’ve come to the right place.

Best Carbine Barrel Pick: Brownells .300 Blackout Barrel & Carbine Gas System Kit
Brownells .300 Blackout Barrel & Carbine Gas System Kit
The Brownells .300 Blackout Barrel & Carbine Gas System Kit ships with a barrel and a gas system that are ready to be installed on your AR-15 .300 Blackout upper receiver. The barrel itself is a sixteen inch carbine length built out of 4150 steel and coated in nitride for excellent durability.

See on Brownells

Best Pistol Barrel Pick: PSA 10.5” CHF .300 Blackout Pistol Gas Barrel
PSA 10.5” CHF .300 Blackout Pistol Gas Barrel
The PSA CHF .300 Blackout pistol barrel is an excellent choice if you are looking to build a .300 Blackout AR pistol. It’s very durable, chrome lined on the inside for an extended service life, has a phosphate coating for good rust and corrosion resistance, and it’s built to military mil-spec standards.

See on Palmetto State Armory

Best Overall Pick: Faxon Firearms .300 Blackout Gunner Profile
Faxon Firearms .300 Blackout Gunner Profile front
The Faxon Firearms .300 Blackout Gunner Profile barrel is available in three different barrel lengths of 7.5 inch, 10.5 inch, and 16 inch. The Gunner Profile barrel design helps to maintain heat better than most other .300 Blackout barrels on the market, which means that it can withstand sustained firing better than most other barrels out on the market.

See on Brownells

One of the most intricately designed parts of a rifle is the barrel. While all parts of the barrel are technically important, it’s the barrel that impacts the accuracy of the rifle the most.

In other words, if you want to improve the accuracy and performance of your AR-15 as much as possible, you will need to upgrade the barrel before you upgrade anything else.

In this article, we will dive into the advantages of the .300 Blackout caliber, the top qualities to look for in a barrel for your .300 Blackout AR-15, and then our choices for the top three best .300 Blackout barrels for 2020.

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History and Advantages of the .300 Blackout

The .300 Blackout is one of numerous calibers that are offered for the AR-15. While the 5.56x45mm NATO and .223 Remington rounds remain the most popular and common rounds for the AR-15, numerous other calibers have been developed over the decades in an effort to improve the shooting performance of the platform.

One of these calibers is the .300 Blackout, which is also known as the .300 AAC or the 7.62x35mm. The .300 Blackout is often confused with the 6.8 SPC round, but the truth is that the two are completely different. Both rounds, however, were developed for the military as potential replacements for the standard 5.56 cartridge.

The .300 Blackout was specifically intended for special forces units. The 5.56 had gained widespread acceptance throughout the military, but in many missions by United States special forces units the need for a round with subsonic performance superior to 9mm was realized. The 9mm was and is the standard issue round for submachine guns in the military just as the 5.56 is for rifles and carbines. One example is the Heckler & Koch MP5 submachine gun in 9mm.

AAC, or the Advanced Armament Corporation, developed the .300 Blackout cartridge in conjunction with Remington Arms in 2009. The idea was that the new round could be used as a subsonic round out of standard M4 carbines that were chambered for the 5.56, and therefore without having to resort to 9mm submachine guns such as the HK MP5.

Furthermore, the military wanted a .30 caliber round could be fired out of an M4 carbine that used normal magazines and bolts, and while also keeping thirty rounds in the magazine as well.

The military had previously tried to accomplish this with other calibers, including the 7.62x39mm like is used in the AK-47. However, it was found that the 7.62x39mm had a bad case angle that resulted in reliability issues unless if specially modified magazines were utilized.

Another round the US military tried to use as a subsonic round were the 6.8 SPC and the 6.5 Grendel, but these results in parts compatibility issues with the 5.56 caliber M4s, and specifically with the magazines. Several calibers were tried as well, including the .300 Whisper, but none could be used in the traditional STANAG magazine either.

The .300 Blackout was officially released in 2011. It delivers energy very similar to the 7.62x39mm, but unlike that round it works well in standard AR magazines loaded to full capacity but there also are plenty magazines for the .300 Blackout on the market.

The .300 Blackout has significant drop and energy loss at long distances, but within five hundred yards it delivers the same amount of energy as the 5.56x45mm NATO. Total effective range of the .300 Blackout is 460 yards.

A big advantage to the .300 Blackout is that it allows a user to use only one caliber while switching between barrier penetrating, subsonic, and supersonic ammunition all the same time. It also performs very well out of short barreled rifles (the .300 Blackout is effective out of barrels as short as four and a half inches) and is therefore a suitable replacement for 9mm submachine guns for use in close quarters.

Weapons chambered for the .300 Blackout can therefore be short, lightweight, compact, and suppressed to be very quiet while offering greater energy and accuracy than pistol caliber weapons.

There is a safety concern to the .300 Blackout that you should be aware of, and that is that you should not mix it with the 5.56 rounds. The two calibers share very similar chamber dimensions, but using a .300 Blackout round in a chamber made for the 5.56 or .223 is simply not safe.

If you own both a 5.56/.223 and a .300 Blackout AR-15, make sure to carefully separate the two weapons and the ammunition. Firing a .300 Blackout in a 5.56 will cause excessive pressure to build up, and it’s possible for the rifle to explode. If you are looking for more parts made for the .300 Blackout, give our articles on .300 BLK BCGs a read.

Should You Go With A Longer Barrel Length For Your .300 Blackout?

Perhaps the biggest factor of all that you should consider when looking at getting a new barrel for your .300 Blackout is the barrel length.

AR-15s are available in numerous barrel lengths, including 10.5 inch, 12 inch, 16 inch, 18.5 inch, 20 inch, 22 inch, and 24 inch. In general, the three most common barrel lengths are the 16, 18.5, and 20 inch, and these are designated the carbine length, mid-length, and rifle length barrels respectively. Anything shorter than a 16 inch will be designated as a pistol under United States law and will need to be used in conjunction with a pistol brace rather than an actual rifle stock in order to be legal.

So which barrel length should you get for your .300 Blackout?

A longer barrel offers many advantages, but many disadvantages as well. Specifically, with a longer barrel you’re going to get a longer sighting plane, or the amount of space in between the rear sight and the front sight. This will improve aiming and accuracy.

You’re also going to have more rifling grooves in a longer barrel. This is important, because you’ll have more surface area for the bullet to spin (which is also referred to as the twist rate). In other words, the bullet will be more stabilized as it travels down the barrel and should offer you superior ballistics at longer ranges.

A longer barrel also means that there will be more room for the powder to burn and the gases of the bullet to expand. This will create a lot more energy for the bullet, which means that will exit the barrel at a faster velocity. The faster the velocity, the faster the greater the effective range of the rifle is.

Furthermore, a longer barrel means that your rifle will likely be quieter, and because the weight will be slightly increased recoil should theoretically be less as well. A longer barrel also means that your rifle will be slightly more effective at longer ranges beyond two hundred and fifty yards.

On the other hand, a longer barrel also means that you sacrifice maneuverability. If you were hoping to use your .300 Blackout as a close quarters self-defense weapon, you’ll want to go with a 16 inch carbine length or a shorter pistol length barrel.

Buyer’s Guide For The Best .300 Blackout Barrels

These are the most important factors to consider when looking for a new barrel for your .300 Blackout AR-15:

Build Material and Finish

AR-15 barrels these days are available in a wide variety of different materials, from aluminum alloy to carbon fiber to blued steel and so on.

It’s also important for the barrel to be coated in a rust and corrosion resistant barrel so it can stand up well against the elements. Cerakote or duracoat coatings are one option, as is a nitride finish. A nitride finish in particular is a common choice to have over a steel barrel, because it offers superior durability, hardness, and lubricity while also resisting moisture and rain well.

Twist Rate

We touched on the twist rate before. The twist rate is basically the number of inches it takes the bullet to travel to make one full rotation before it exits the barrel. A twist rate of 1:7, for instance, means that the round will travel seven inches to make a complete rotation.

As a golden rule, a lower twist rate will result in more accurate shots. Furthermore, a lower twist rate is a good choice to have for supersonic ammunition such as the .300 Blackout and will absolutely be necessary if you plan on shooting the firearm at longer range.


Weight is one of the most overlooked factors when selecting a barrel. A heavier barrel will be more stable, cool off more quickly, and help keep recoil down for faster and more accurate follow up shots. But of course, the negative aspect of a heavier barrel is that it will not be as fun to carry around for extended periods.

The 3 Best .300 Blackout Barrels For 2020

Now that we’ve covered why you need to upgrade your .300 Blackout barrel, here are our picks for the top three best .300 Blackout barrels for 2020:

Faxon Firearms .300 Blackout Gunner Profile

Faxon Firearms .300 Blackout Gunner Profile front

The Faxon Firearms .300 Blackout Gunner Profile barrel is unique for its gunner profile, which according to Faxon is designed to provide the right combination between heat dissipation and weight. Specifically, the Gunner Profile means that the barrel has a pencil profile before the gas block in order to keep the weight down and preserve the ease of handling.

Meanwhile, the part of the barrel behind the gas block is enlarged to have more material, which helps to withstand extreme heat. This means that the Faxon should theoretically be able to hand sustained firing and heat better than other barrels can.

Faxon Firearms .300 Blackout Gunner Profile

The Faxon is available in three different barrel lengths of 7.5 inch, 10.5 inch, and 16 inch. It has a back QPQ nitride finish with an additional NP3 coating, which makes it as rust and corrosion resistant as you can possibly ask for. The muzzle at the end of the barrel is threaded with 5/8-24 threads, which makes it fully compatible with several muzzle devices on the market. The 5R rifling design of the barrel also helps to improve accuracy as well.

Faxon Firearms .300 Blackout Gunner Profile back


Overall, the Faxon Firearms is an excellent choice for a .300 Blackout barrel. The Gunner Profile design helps the barrel to handle sustained firing better than many other .300 Blackout barrels on the market, and the QPQ nitride coated finish and NP3 coating makes it as rust and corrosion resistant as you could ask for.

  • Designed specifically to handle extended shooting sessions
  • QPQ nitride coated finish for solid rust and corrosion resistance
  • Has a unique Gunner Profile design
  • Comes NP3 coated to extend the life of the barrel
  • 5R rifling design helps to improve accuracy
  • Available in three different barrel lengths – 7.5 inch, 10.5 inch, and 16 inch
  • Designed to withstand sustained fire well
  • Will most likely require additional fitting to your AR-15

PSA 10.5” CHF .300 Blackout Pistol Gas Barrel

PSA 10.5” CHF .300 Blackout Pistol Gas Barrel
If you are looking for a short pistol length barrel for your .300 Blackout AR-15, you’ll want to take a close look at the Palmetto State Armory (PSA) 10.5” CHF .300 Blackout pistol gas barrel. This barrel is hammer forged out of chrome moly vanadium steel and is also chrome lined on the inside of the barrel in order to extend its overall service life. The chrome lined barrel is considered to be military standard for this same reason.

The 1:8 twist rate of this barrel is very optimal for stabilizing the .300 Blackout round out of such a short barrel. Meanwhile, the chamber has been heat pressure tested and carefully inspected for any flaws in its construction. The outside of the barrel has been coated in a mil-spec grade phosphate to help improve durability and rust and corrosion resistance as well.

As a pistol barrel, the PSA CHF will need to be used on an AR-15 with a brace and not a stock; otherwise it will not be legal under United States law unless if you have the proper licensing.

Overall, the PSA CHF pistol barrel is one of the best choices for a .300 Blackout AR pistol. Built to military specifications, it’s very durable and rust resistant, and is chrome lined to help extend its overall service life. As a pistol barrel, it will be very maneuverable in tight conditions for home defense, but less adept for shooting rounds at longer ranges.

  • Short length is great for shooting in tight conditions
  • Designed to manage heat well from extended shooting sessions
  • Very durable construction thanks to the chrome moly vanadium steel
  • Chrome lined on the inside for extended service life
  • Has a phosphate coating on the outside for good rust and corrosion resistance
  • 1:8 twist rate is optimal for a shorter barrel length
  • Short length is not good for longer ranges

Brownells .300 Blackout Barrel & Carbine Gas System Kit

Brownells .300 Blackout Barrel & Carbine Gas System Kit
The Brownells .300 Blackout Barrel and Carbine Gas System Kit is not just a barrel, but an entire kit consisting of a barrel and a gas system along with a roll pin and low profile gas block. This is ready to install on a carbine-length .300 Blackout upper receiver, which you can then combine with your .300 BLK lower receiver.

The barrel of the Brownells is built out of 4150 steel and has a nitride finish over the surface for superior rust and corrosion resistance. The barrel is sixteen inches long and has a 1:8 twist rate. The gas system is carbine length, which will give you added velocity over an AR pistol.

This is also a low profile barrel that is designed to be easily hidden underneath a free floating hand guard, which will help create a more streamlined look for your AR-15. The muzzle is 5/8-24 threaded to enable you to add a variety of different muzzle brakes for your blackout.


All in all, the Brownells .300 Blackout Barrel & Carbine Gas System kit is an excellent value that allows you to customize your existing gas system. The sixteen inch barrel will offer superior velocity to a pistol length barrel, and the 4150 steel construction and nitride finish means that it’s ready to be used out on the field in poor conditions.

  • Very durable
  • 4150 steel construction is highly durable
  • Comes with gas system so the kit is ready to help build your upper
  • Comes with a rust and corrosion resistant nitride finish
  • Has a SOCOM-style contour
  • Very low profile
  • Has a 1:8 twist rate
  • The kit lacks instructions, so you’ll have to do your research online on how to install it

Wrap Up

And that concludes our list of the top three best barrels for an AR-15 in .300 Blackout.

The .300 Blackout is a truly overlooked and underrated caliber, and the number one best thing that you can do to improve its performance as much as possible out of your AR will be to upgrade the barrel.

Any one of the three barrels that we have covered here today will be a good option, and you can also refer to the buyer’s guide section above to help you find an excellent and high performing barrel for your .300 Blackout as well.

Featured image by u/ccguns

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