.300 Blackout rifle

Best .300 Blackout Uppers

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One of the nice features of the AR-15 is the ability to alter the upper receiver to fit a wide range of ammunition. The design of the 300 Blackout cartridge allows shooting it from AR-15 rifles. Now, as it does not have the same reliability issues as other cartridges, upgrading the AR-15 to accommodate the 300 Blackout could also upgrade your AR-15 game.

If you are looking for a new upper receiver for your .300 Blackout AR-15, you’ve come to the right place. We’ll go over these great options:

  • PSA 8.5” .300 Blackout Complete Upper Receiver: Best Compact Upper Receiver
  • PSA 10.5” .300 Blackout Complete Upper Receiver Kit: Best Upper Receiver Kit
  • PSA 16” .300 Blackout Upper Receiver: Best Carbine Length Upper Receiver
  • Primary Weapons MK109 Pro Complete Upper Receiver: Best Overall Upper Receiver
  • Aero Precision M4E1 Assembled Upper Receiver: Best Upper Receiver Pistol Option
  • Bravo Company 9’’ .300 Blackout Upper Receiver: Best Top-Tier Upper Receiver

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Why Go With .300 Blackout Round?

The .300 Blackout also known as the .300 AAC is only one of many different rounds for the AR-15. Manufacturers developed the 300 Blackout for AR-15s with barrels that are shorter than typical. It’s also one of many rounds designed to enhance the performance of the AR-15 over its standard calibers.

Let’s take a look at the advantages of the .300 Blackout round:

  • Possible to switch from supersonic to subsonic ammo without changing the gas system
  • Create full-power ammo that is compatible with 7.62×39 ballistics
  • It’s simple to convert your existing 5.56 or .223 AR-15 to .300 Blackout
  • Can use many existing stock magazines
  • With high-mass projectiles, it is capable of penetrating barriers
  • Create the ideal platform for sound and flash suppression fires
  • Good capabilities such as lightweight, sturdy, and low recoil

The company Advanced Armament Corporation designed the 300 Blackout. They have also tested it thoroughly to ensure that it fits perfectly in your AR-15 magazine. So, if you want to try this ammo, all you have to do is get a .300 Blackout upper, install it on your AR-15, and you’re ready to go!

Best .300 Blackout Uppers 300 Blk 125 gr, 300 Blk 150 gr, 300 Blk 220 gr, 5.56mm NATO, 7.62x39mm
300 Blk 125 gr, 300 Blk 150 gr, 300 Blk 220 gr, 5.56mm NATO, 
7.62x39mm; Wikipedia

The .300 Blackout Usefulness

The .300 Blackout’s main use is to provide AR-15 users with subsonic capabilities. The majority of US soldiers have issued 9mm submachine guns to have a weapon that’s quieter than a 5.56 with a silencer. Furthermore, the .300 Blackout can perform a lot of things that the 5.56 can’t. First, you got both supersonic and subsonic, with the 110-grain rounds going supersonic and the 220-grain rounds subsonic. Second, the .300 Blackout achieves the greatest ballistic potential with a 9” barrel. Meanwhile, the 5.56 requires a 20” barrel.

Existing M4 carbines with shortened barrels might now be used with the .300 Blackout. This is possible without having to use a pistol-caliber weapon such as the HK MP5. Submachine guns, such as the MP5, are small and convenient to carry anywhere. They also use pistol caliber rounds, which are less powerful than rifle rounds.

Best .300 Blackout Uppers 300 Blk rounds shot from a suppressed M4 carbine
300 Blk rounds shot from a suppressed M4 carbine; Photo credit: Wikipedia

With the .300 Blackout, you could still use 6” to 9” barreled M4s in a tactical setting. You can use it with suppressors without sacrificing stopping power. You need to switch an M4 or AR-15 from a 5.56 to .300 Blackout barrel and certain upper receiver components.

Put the .300 Blackout in an AR-15 in conjunction with a silencer, and it will create less noise than a 5.56 or .223 round. The amount of recoil is also minimized. When shooting the .300 Blackout, the kick and noise should be more like a .22 LR than an actual 5.56.

What Does The .300 Black Upper Receiver Do?

Every AR-15 can be stripped into two parts: the upper receiver and the lower receiver. A barrel, bolt carrier group, handguards, and the rail system make up the upper receiver.

The upper receiver on an AR-15 can be swapped out for different calibers. This makes switching between calibers far cheaper than if you had to buy a whole new rifle or carbine.

Why Should You Upgrade Your Upper Receiver?

There are many reasons to upgrade your upper receiver from the one that shipped to you out of the factory. An upper receiver is the part of the gun that impacts accuracy the most. Especially, if it comes with a free-floating handguard. Therefore, if your existing upper receiver is not free-floating, you should consider upgrading it because your rifle could potentially become up to 50% more accurate.

Another reason you may want to upgrade is if your existing gun does not come with all the features that you need. For instance, budget upper receivers often work well enough. But, it also comes with lower quality bolt carrier groups. Sometimes lack a dust cover or a forward assist. Also, while neither a dust cover nor forward assist are necessary for an AR-15 to work, they can both help out with reliability in bad conditions.

Finally, another reason to upgrade is if you want your upper to match better with your lower receiver. It’s a good idea for both your upper and lower to come built out of the same materials and to have the same finish. This is not only for looks, but also to ensure reliability when firing.

Buyer’s Guide For a .300 Blackout AR-15 Upper Receiver

Factors to consider when looking for a new upper receiver for your .300 Blackout AR-15:

Should You Get Stripped or Complete?

A stripped upper receiver means that the receiver is not ready to use out of the box. Some components are lacking, which you will have to add yourself. While it adds a bit of work, it allows you further customizations and more personalization. 

Complete upper receivers come ready to go out of the box. They have everything already installed in them. In other words, if you get a complete upper along with a complete lower, you can put them together and you should have a fully functioning rifle or carbine ready to go.

Durability and Corrosion Resistance

Your upper receiver is literally half of the firearm and includes the barrel. For this reason, it needs to be as durable as possible. The best materials to go with for an upper receiver for your AR-15 must be 7075-T6 aluminum. This is an aircraft-grade aluminum that is durable and also lightweight. For reference, the Beretta 92FS 9mm service pistol comes built of the same materials.

To make your firearm more corrosion-resistant to rain and moisture, you have options. A nitride finish is one option, and another is to go with a blackened hard coat anodized finish. Both of these are very rust resistant and should serve you well. They also add durability to the aluminum.

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Make Sure It Has a Rail

If your upper receiver has a Picatinny rail on the top, it will be very easy for you to add sights, lasers, or scopes. Many upper receivers do not come with sights installed including complete uppers. So you will need to buy these separately and then add them to your rail.

It Should Come With A Dust Cover and Forward Assist

As noted before, neither a dust cover nor forward assist are truly necessary for an AR-15 to work. But they can also greatly enhance reliability in rough conditions. The dust cover is designed to keep the elements out of your chamber before firing. On the other hand, the forward assist is designed to help clear a malfunction.

So long as you’re going to invest money into a new upper receiver, it should come with both the cover and the assist. Both will be nice features to have when you need them.

The Best .300 Blackout Upper Receivers

Now that we’ve covered why you should upgrade your upper receiver and what are the top qualities to look for. Here’s our top pick for the best . 300 Blackout upper receiver:

PSA 8.5’’ .300 Blackout Complete Upper Receiver

The PSA 8.5” .300 Blackout is a solid upper receiver if you are looking for a compact pistol length option. This upper is ideal for tactical and hunting purposes. It is also much more maneuverable in tight conditions. In addition, the receiver itself is built out of 7075-T6 aluminum and has a hard-coated anodized finish. Thus, it is wear and tear-resistant, as well as being highly durable and lightweight.

When it comes to the barrel, it has superior corrosion resistance because of its nitride finish. Additionally, the PSA 8.5″ is designed to handle supersonic rounds with excellent precision. Also, the bolt carrier group is built out of 158 Carpenter steel. Another solid component. Lastly, the M-Lok handguard is already equipped for an easy mount of sights and accessories.

Overall, the PSA 8.5” .300 Blackout Upper Receiver is a solid choice for compact use. You can mount it on both a pistol lower or a regular rifle lower. Furthermore, it comes with a durable aluminum build anodized finish for excellent rust resistance. Finally, the barrel itself is designed to handle supersonic rounds with the utmost precision.

Pros
  • Has a 1:7 twist rate
  • Comes with a full-length rail
  • Hard coat anodized finish is very rust resistant
  • Comes with M-Lok handguards
  • Compact and maneuverable in tight conditions
  • Barrel is designed to handle supersonic rounds
Cons
  • Not good for long-distance shooting
  • Cannot be easily customized

PSA 10.5” .300 Blackout Complete Upper Receiver Kit

This is not just a PSA 10.5” .300 Blackout Upper Receiver, it’s also an entire kit. You’ll get the upper receiver as well as everything else you’ll need to finish the weapon, except for the lower receiver. That one you’ll need to get separately.

This upper receiver features a pistol-length gas system and an A2 profile barrel. The interior of the barrel features a 1:8 twist rate that is optimal for the .300 Blackout round. Furthermore, the receiver is built out of forged aluminum and has a 12-inch M-LOK handguard installed over it.

The barrel of the muzzle features 5/8-24 inch thread that makes it easy to add suppressors and muzzle brakes. The kit also includes a pistol grip, buffer tube, fixed stock, and other components.

This kit will complete the rifle for you. All you’ll need is a stripped lower receiver that is compatible with a .300 Blackout upper. In short, it comes with everything you need to build your own .300 AAC AR-15.

Pros
  • Lightweight and compact
  • Comes with a full assembly kit (all you need to buy is a stripped lower receiver)
  • Has excellent maneuverability
Cons
  • The trigger is a little bit heavy

PSA 16” .300 Blackout Upper Receiver

The PSA 16” .300 Blackout Upper Receiver sports 7075 T6 aluminum material and has an M4-type design. It is complete with a .300 Blackout bolt carrier group, forward assist, handguard, and a barrel. In addition, PSA built the bolt carrier group out of 158 carpenter steel and it has a rugged design with a fully automatic profile (even though it is only capable of semi-automatic firing in its existing configuration). The entire upper is also coated in nitride for added rust and corrosion resistance. The pistol-length gas block is ideal for the .300 Blackout round as well.

PSA built the barrel out of durable chrome-moly vanadium 4150V. Colt developed this for their military-issued M16 and M4, so strong stuff. In addition, the barrel has a heavy profile. It means that it can shoot through several magazines without running into other issues. As with the rest of the upper, the barrel comes with a nitride finish for excellent rust resistance as well. Additionally, its barrel end equips itself with 5/8-24 threads. It can therefore easily accept most muzzle brakes and suppressors.

This upper comes with an A2 flash hider, Picatinny rail, and a free-floating handguard. IOn my view, the 16” barrel also offers a good option between the longer 20” barrels and the shorter ones.

Overall, the PSA .300 Blackout 16” Upper Receiver is a solid choice if you want a carbine-length upper. However, it does not come with sights, so you will need to add those yourself.

Pros
  • Durable construction from 7075 T6 aluminum
  • The complete upper receiver, so it’s ready to go out of the box
  • Comes with a free-floating handguard
  • Barrel is made out of 4150V chrome moly vanadium
  • 1:8 twist rate of the barrel is ideal for .300 Blackout
Cons
  • Does not come with sights

Primary Weapons MK109 Pro Complete Upper Receiver

The Primary Weapons MK109 Pro is a complete upper receiver. It comes ready to install with a .300 Blackout lower right out of the box.

This receiver comes with a free-floating M-LOK handguard and a short 9.75-inch barrel, also with a 1:8 twist rate. It also has an adjustable gas system and a Radian Weapons Raptor charging handle. It does not come with sights, so you’ll need to add those yourself.  The MK109 has a Picatinny rail that makes it easy to add optics and other accessories.

Best .300 Blackout Uppers MK109 Pro Receiver
Photo credit: Brownells

The MK109 Pro receiver sports its 7075-T6 aluminum material. It has a blackened anodized finish, which means it holds up well from rain, snow, or moisture. The total weight of the MK109 is just over three and a half pounds, which makes it a very lightweight option as well.

Best .300 Blackout Uppers MK109 Pro
Photo credit: Brownells

Looking for a solid .300 AAC upper receiver built out of the highest quality components? You’ll want to check out the MK109 Pro! This complete upper receiver comes with excellent features. In addition, this has an adjustable gas system. It features a free-floating handguard, a charging handle, and a durable aluminum build.

Pros
  • Has a 1:8 twist rate
  • Comes complete and ready to go right out of the box
  • Comes with a long stroke system
  • Has a free-floating handguard
  • The gas system is adjustable
  • Radian Weapons Raptor charging handle
  • Built out of 7075-T6 aluminum with an anodized finish
Cons
  • Very expensive
  • Does not come with sights

Aero Precision M4E1 Assembled Upper Receiver 

Aero Precision’s .300 Blackout uppers provide a modern style and high-quality AR components. It differs from regular MIL-SPEC uppers in several ways. This upper is built with an 8-screw handguard that accepts a free-floating handguard. In addition, the Aero’s M4E1 .300 Blackout upper is available in 8″ and 10″ barrel lengths. This upper is best suited for a pistol built with an 8″ barrel format. The M4E1 is forged from 7075-T6 and CNC-machined for a clean and secure fit. Also, the barrel is made of chrome-moly vanadium and has a QPQ corrosion-resistant finish.

The handguards on these Aero uppers come in a variety of lengths to accommodate the attached flash suppressor. You can remove the flash hider and install a muzzle brake or suppressor instead. Additionally, you’ll find a gas system that’s about the size of a handgun here. The M4E1 uppers also come with Keymod rail systems and are chambered for the.300 Blackout round. Moreover, the upper comes with a typical M4 feed ramp, which improves carbine and pistol accuracy.

This upper receiver is built from the bottom up to be simple to operate. This is a pre-assembled kit ready for installation on your lower receiver. However, one drawback is that this doesn’t come with a bolt carrier group or charging handle. You’ll need to get that separately. However, this upper should be compatible with those from your current AR-15.

Pros
  • Forged 7075-T6 and CNC-machined for a tight and secured fit
  • Suitable for 8’’ barrelled pistol build
  • A suppressor or muzzle brake can be added
  • Easy to install and use
  • Corrosion-resistant
Cons
  • There is no bolt carrier group or charging handle included

Bravo Company 9’’ .300 Blackout Upper Receiver

Bravo Company (BCM) 9″ barrel upper with an 8″ M-LOK handguard is our choice for the top .300 Blackout upper. BCM produces products that are comparable to other companies at a reduced cost. As a result, its products are the best bang for your buck.

The 9″ barrel on this 300 Blackout upper is ideal for the 300 BLK cartridge. Combined with a lower, this thing is an ideal home defense and even hunting setup. Additionally, the barrel is chrome-lined for added durability, corrosion resistance, and heat tolerance. This 2.2-pound upper is made of a MIL-SPEC Manganese Phosphate finish with an outside coating to prevent pitting, rust and scratching. This upper comes without a bolt carrier group or charging handle, much like the Aero. These barrels are compatible with both a carbine buffer, subsonic and high-velocity ammunition. However, BCM cannot guarantee that all ammo types will function in all conditions.

In comparison to the USGI version, this patented design provides increased stiffness. Because of the increased rigidity, barrel deflection is reduced. This, in turn, improves consistency and accuracy. Moreover, less flex is beneficial because misalignment can cause damage and bolt lugs failure.

Overall, this upper is an excellent buy. It includes a 3-inch Picatinny Rail and MCMR Sling Mount. It also has a standard 30 cam Muzzle thread and MCMR-8 free-floating handguard. With all these features, what more could you ask for?

Pros
  • Chrome-lined barrel for longevity
  • Corrosion and heat resistant
  • MIL-SPEC Manganese Phosphate finish
  • Compatible with subsonic and high-velocity ammo
  • Comes with MCMR-8 handguard, Sling Mount, and 3’’ Picatinny Rail
Cons
  • Does not include bolt carrier group and charging handle
  • Not suited for all ammo type

The Final Word

That concludes our list of the best .300 Blackout upper receivers. The .300 Blackout is an overlooked round that has the potential to boost the true potential of your AR-15. This time, you already knew how to maximize its usage. 

If you want an upper receiver group that works right out of the box, get a full upper receiver with a bolt carrier group and charging handle. Remember that you can keep your 5.56 lower if you install a .300 Blackout upper and barrel.

Do you want to learn more about the .300 Blackout? Read our guides to:

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  1. My first build was a PSA .300 AAC Upper 3 years ago. At that time the completed upper was $299. The Lower Parts kit I had to purchase separately. Built as a pistol, it has been a pleasure to shoot, and it’s staged as my home defense gun.
    I guess if the Brace Bab goes through, I’ll have to apply for a Tax Stamp (hopefully it doesn’t go through). I haven’t applied for a Suppressor stamp yet. I did put a Witt Tool Company Sound mitigation brake on the barrel, and noticed maybe a 10 to 20% drop in the report (the Witt focuses sound forward).
    I agree with you Beau, .300 AAC is a great option, and in my State, you could hunt deer with the .300, but not with the 5.56. Ballistically, it’s similar to 30-30. A buddy of mine in Texas uses his .300 AAC for Feral Hog shooting, and has great results.

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