.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. .300 Blackout is one of the best designed so far and gives you 7.62×39 Soviet ballistics in the AR-15 platform. All you need is one of the Best .300 Blackout Uppers!

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 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 the .300 Blackout Round?

The .300 Blackout also known as the 300 AAC or 300 BLK is only one of many different rounds for the AR-15. Designed to be quiet when suppressed and to give 7.62×39 Soviet ballistics in the AR-15 platform, 300 BLK is a great hard hitting round.

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
  • 7.62×39 Soviet 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.

During the ’80s and ’90s when USSOCOM wanted to do sneaky quiet things they turned to 9mm Luger for their suppressed weapon needs, often using MP5s to do so.

While the M4 and its predecessors were in common use, 5.56 NATO isn’t as quiet as they wanted it to be. It also tends to have very poor performance when shot subsonic.

A fix was needed and to answer the call, .300 Blackout was invented.

Basically coping 7.62×39 ballistics, but designed to use standard M4 bolts and magazines, the only thing required to change from 5.56 NATO to .300 BLK is a new barrel. This combined with the ease of use make it a huge winner in the special forces commonity.

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

On the civilian side 300 BLK has proven to be a great cartridge for home defense, hunting, and general use.

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. But it might also take some tools like a barrel nut wrench and vise.

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.

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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It Should Come With A Dust Cover and Forward Assist (If You Want One)

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. Personally, I agree with the man who designed the AR-15 and say that the forward assist causes far more problems than it ever solved.

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 highly durable and lightweight.

When it comes to the barrel, it has superior corrosion resistance because of its nitride finish.

The bolt 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, but beware of the NFA and Short Barreled Rifle law if you do.

  • Has a 1:7 twist rate
  • Comes with a full-length rail
  • Hard coat anodized finish
  • Comes with M-Lok handguards
  • Compact and maneuverable in tight conditions
  • Not good for long-distance shooting

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.

Just like the 8.5″ version, this also uses a bolt made from 158 carpenter steel and it has a rugged design. The entire upper is also coated in nitride for added rust and corrosion resistance.

PSA built the barrel out of durable chrome-moly vanadium 4150V.

Colt developed this for their military-issued M16 and M4, so strong stuff.

As with the rest of the upper, the barrel comes with a nitride finish for excellent rust resistance as well. Lastly, the barrel is threaded 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.

All in all, this is a great option for a rifle-sized 300 BLK gun.

  • 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
  • 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.

What sets this apart from anything else is the Long Stroke Gas System. While most uppers use Direct Impingement, PWS are masters of the piston rifle. This makes for a nicer suppressor experience and a cleaner shooting gun.

Looking for a solid .300 AAC upper receiver built out of the highest quality components? You’ll want to check out the MK109 Pro!

Primary Weapons has a long history of making really high-quality units and this is no exception. If you want a fighting rifle, this is a solid pick. Being a piston gun, this is also just a really cool choice for best .300 Blackout upper.

  • 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
  • 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 and 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 and 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

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.

  • Forged 7075-T6 and CNC-machined for a tight and secured fit
  • Suitable for 8″ barrelled pistol build
  • Easy to install and use
  • Corrosion-resistant
  • 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.

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.

Sadly, like Aero’s upper, this upper does not include a bolt carrier group or charging handle.

However, something that really makes BCM stand out is their hyperattention to detail and their unbelievable quality control.

All firearms should be held to high standards, but BCM constantly turns out a product that is a level up on the rest of the industry and has really pushed others to improve their processes so that they can try to keep up.

Overall, this upper is an excellent buy.

  • Chrome-lined barrel for longevity
  • Corrosion and heat resistant
  • MIL-SPEC Manganese Phosphate finish
  • Comes with MCMR-8 handguard, Sling Mount, and 3″ Picatinny Rail
  • Does not include bolt carrier group and charging handle

The Final Word

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:

1 comment
  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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