The Best 300 Blackout Uppers for Completing Your 300BLK Rifle

Last Updated on October 8, 2020.

One of the best things about 300 Blackout is that a 300BLK rifle is basically just a 5.56mm rifle with a .30 caliber barrel. So you can just slap one of the best 300 Blackout uppers on your favorite lower receiver. Then—BOOM—you’ve got a 300AAC rifle.

So a 300 Blackout upper is actually a great part to have. A 300BLK upper enables you to shoot multiple calibers, without purchasing a whole new firearm.

But 300 Blackout is pretty popular these days. There are a lot of potential best 300 Blackout uppers out there. It would take quite a while to sort through all of them. So we sorted out all the best 300 Blackout uppers for you.

WHY YOU SHOULD BY THIS

This is an affordable, maneuverable upper that performs quite well.

BENEFITS

  • Durable, long lasting chromoly vanadium barrel.
  • 1 in 8 inch twist works well with typical civilian bullet weights.
  • True mil-spec Carpenter 158 steel bolt.
  • Durable, corrosion resistant phosphate coated barrel and bolt carrier group.
  • SPOILERthe PSA 10.5" Pistol-Length 300AAC came out on top as the best 300 Blackout upper. There’s a caveat with this upper. But, overall, it’s a very affordable upper receiver that also performs quite well.

    If you’re looking for something different—or maybe you’re just not a fan of Palmetto State Armory—keep reading. We’ve got all the best 300 Blackout uppers for you to check out.

    Top 300 Blackout Uppers on the Market Today

    Best 300 Blackout Uppers Reviews: The Upper Half

    The overall best 300 Blackout upper is up for review first. The other best 300 Blackout uppers will be presented in order of price.

    Need the best 300 Blackout upper for the money? Read the first reviews.

    Need the best 300 Blackout upper if money were no object? Read the reviews near the end.

    Let’s put some uppers on some lowers.

    1. PSA 10.5" Pistol-Length 300AAC - Overall Best 300 Blackout Upper

    • Model: PSA 10.5" Pistol-Length 300AAC
    • Barrel length: 10.5 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 8 inches
    • Forend attachment system: M-LOK

    The PSA 10.5" Pistol-Length 300AAC is a really affordable complete upper receiver. And it’s good enough that most shooters won’t be able to tell the difference between this and a more expensive upper receiver, with one caveat, which I’ll get to shortly.

    First, though, this is almost just a mil-spec upper receiver with an upgraded handguard.

    The barrel is chromoly vanadium, cut with a 1 in 8 inch twist and capped with an A2 compensator. The rate of twist is a bit slower than a true mil-spec barrel to give you better ballistics with typical civilian ammunition.

    Then, both the barrel and bolt carrier group are phosphate coated. It’s the standard mil-spec coating. It’s super durable and corrosion resistant. It just doesn’t look as cool as something like a black nitride finish.

    Additionally, the bolt itself is constructed from Carpenter 158 steel, which is the original mil-spec steel. And I prefer C158 steel bolts because there’s less variance in the steel quality. So it’s less likely that you’ll get a C158 steel bolt that’s too brittle or not tough enough.

    The caveat with this upper is that Palmetto State Armory firearms and uppers occasionally ship without being correctly assembled. The individual parts are correctly manufactured, but they’re put together wrong. And if you fired the gun without being correctly assembled, you could cause permanent damage to your otherwise good components.

    As such, I recommend that you either do a thorough inspection yourself, or have a gunsmith check this upper, before you slap it on a lower receiver and start cranking off rounds.

    But, as long as everything is put together the right way, this upper receiver is an excellent option for anyone who wants an affordable upper receiver that delivers enough performance for just about anything.

    Also, if you want a longer or shorter barrel, or a different handguard, this upper receiver comes in other configurations:


    • Model: Radical Firearms 16 in. 300 AAC Blackout Upper Assembly
    • Barrel length: 16 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 8 inches
    • Forend attachment system: Picatinny quad rail, M-LOK, KeyMod

    Some shooters bag on Radical Firearms because they make really affordable firearms. But Radical Firearms guns run just fine. So the Radical Firearms 16 in. 300 AAC Blackout Upper Assembly is a great option for anyone who needs a really affordable upper receiver that’s good enough for just about anything.

    First, the barrel on this upper receiver is a 16-inch chromoly vanadium barrel that’s cut with a 1 in 8 inch twistThe barrel steel is super long lasting. And the rate of twist gives you better ballistics with common 55 grain ammunition.

    Then, almost everything—the bolt carrier group, the barrel, and muzzle device—on this upper receiver is finished in black meloniteIt’s a durable and corrosion resistant finish that also looks way cooler than the traditional phosphate finish.

    The melonite finish also makes the bolt run smoother and require less lubrication. It might be a minor improvement, but the melonite finish also helps improve reliability.

    Also, you can get this upper receiver with any handguard configuration that you like: picatinny quad rail, M-LOK, or KeyMod.

    Lastly, this Radical Firearms upper receiver is also available with a 12-inch or 8.5 inch barrel, for those who want a short platform.

    Overall, if you want a super affordable upper receiver that’s got quite a few features that you usually find on more expensive uppers, this is the upper receiver for you.


    • Model: Ghost Firearms Elite .300 Blackout Upper Receiver
    • Barrel length: 7.5, 10.5, or 16 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 8 inches
    • Forend attachment system: M-LOK

    The thing that makes the Ghost Firearms Elite .300 Blackout Upper Receiver the best 300 Blackout upper for the money is the configuration options. This upper receiver comes with just about any barrel length.

    Now that I said it, here are the details: this upper receiver is available with a 7.5, 10.5, and 16 inch barrel. No matter what type of rifle or pistol you want, this upper receiver comes with a barrel length that will meet your needs.

    Additionally, the barrel is a light HBAR, hybrid barrel profile. It’s lighter than a true HBAR profile. But it’s also more precise and heat resistant than a pencil barrel. It’s kind of the best of both worlds, in terms of weight and precision.

    Also, the barrel is finished in black melonite to give you the corrosion resistance you need, with better looks than a phosphate finish.

    Lastly, the handguard is a free float handguard with M-LOK attachment points. There are no M-LOK slots at the diagonal positions. But the handguard is cut to keep the weight down, even if they have to sacrifice a couple rows of M-LOK slots to save that weight.

    The catch with this Ghost Firearms upper is that it does not come with a 300 Blackout BCG or charging handle. That’s not a huge deal for a 300 Blackout upper, because you can use your 5.56mm bolt carrier group. But it would be nice to get a fresh bolt carrier group with your upper.

    However, omitting the bolt carrier group enables Ghost Firearms to keep the price low and the component quality high. That way you get an outstanding upper receive for a really good price.


    • Model: Aero Precision M4E1 .300 CMV Barrel Complete Upper Assembly
    • Barrel length: 8, 10, or 16 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 7 inches
    • Forend attachment system: Picatinny quad rail, M-LOK, or KeyMod

    Aero Precision components offer some of the best performance-per-dollar that you can get. The Aero Precision M4E1 .300 CMV Barrel Complete Upper Assembly is an impressively affordable upper. And the quality is outstanding.

    First, this receiver is fitted with a 4150 chromoly vanadium barrel. The twist rate is 1 in 7 inches, which is the mil-spec standard. It works best with heavier bullets. But it will still sling 55 grain bullets just fine.

    Also, the barrel is finished with a black QPQ finishThe finish looks really sleek. And it’s super durable and corrosion resistant.

    One more thing about the barrel: You can get this upper receiver with an 8 inch barrel10 inch barrel, or a 16 inch barrel. So you can get the upper receiver that matches your range and maneuverability requirements.

    Additionally, this upper receiver is fitted with an Aero Precision handguard. Aero Precision handguards are some of the best you can get. All of the Aero Precision handguards have superb ergonomics. And they’re super easy to remove and install, if you need to do some sort of maintenance that requires removing the handguard.

    Also, you can get this upper receiver with an M-LOKKeyMod, or picatinny quad railThat way you can add any forend attachments that you have on hand.

    Unfortunately, this model doesn’t come with a bolt carrier group or charging handle.

    But this Aero Precision upper receiver will deliver outstanding performance with whatever bolt carrier group you feed it. And the ergonomics and aesthetics are incredible.


    5. CMMG, Inc. RESOLUTE 100 Series Upper Receiver Group - Long Range 300 Blackout Upper

    • Model: CMMG, Inc. RESOLUTE 100 Series Upper Receiver Group
    • Barrel length: 16 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 7 inches
    • Forend attachment system: M-LOK

    The CMMG RESOLUTE series is designed to be an all-purpose rifle. However, the barrel length and design make the CMMG, Inc. RESOLUTE 100 Series Upper Receiver Group an excellent upper for anyone who wants an exceptionally precise 300 Blackout rifle.

    This upper is fitted with a 16 inch barrel, which delivers as much muzzle velocity as you might need for long range shooting.

    The barrel is cut with a 1 in 7 inch rate of twist, which is best for shooting heavy bullets. It’s ideal for most match and hunting ammunition. And the barrel profile is a medium taper profile, which puts a lot of metal around the chamber, where you need the most material for precision and heat resistance.

    Lastly, the barrel is finished in salt bath nitrideThe finish is incredibly corrosion resistant. And the finish looks great.

    Also, the A2 compensator can be easily removed if you want to add a more capable muzzle device.

    Overall, the barrel produces excellent performance for long range shooting.

    Then, there’s all the other parts.

    The handguard is a free float M-LOK handguard that extends almost to the muzzle. It’s handy if you want to attach a bipod, because it places the bipod where it gives you the most muzzle stability.

    CMMG uses 9310 steel bolts. I’ve seen a lot of CMMG bolts. And so far none of them have failed. So it seems that CMMG uses high grade 9310 steel to ensure that their bolts last as long as they’re supposed to.

    Ultimately, if your goal is to build a 300 Blackout rifle that will produce nice tight groups at max range, this CMMG upper will be a great fit.


    6. Primary Weapons Systems MK109 MOD 2-M - Gas Piston 300 Blackout Upper

    • Model: Primary Weapons Systems MK109 MOD 2-M
    • Barrel length: 9.75 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 8 inches
    • Forend attachment system: M-LOK

    The Primary Weapons Systems gas piston system is one of the best on the market. So the Primary Weapons Systems MK109 MOD 2-M is the best upper you can get, if you want a gas piston upper.

    The main reason that I like this gas piston system is the recoil impulse.

    Most gas piston systems are fairly violent and produce a relatively snappy recoil impulse. The PWS gas piston system vents off gas gradually to slow the bolt carrier down as it gets closer to the rear. That way the recoil impulse is smoother and easier to manage during rapid fire.

    And you still get less carbon in your action for more reliability with less cleaning.

    Additionally, this upper comes with better than mil-spec hardware. The charging handle is a Radian Raptor charging handle, which is by far one of the best charging handles you can get. Many people say it’s the best.

    Additionally, all the coatings and finishes are better than mil-spec. Even the hard coat anodizing is better than the standard mil-spec coating.

    Coming back to the gas system, this upper still has a slightly more aggressive recoil impulse than a well-tuned direct impingement rifle.

    But the recoil impulse is still totally manageable. And, if you want a gas piston gun, this PWS upper has one of the most mellow recoil impulses of them all.


    7. Radian Weapons Model 1 .300 AAC Blackout Complete Upper Receiver - 300 Blackout Upper for Suppressed Shooting

    • Model: Radian Weapons Model 1 .300 AAC Blackout Complete Upper Receiver
    • Barrel length: 9 inches
    • Barrel metal: 4140 chromoly vanadium
    • Rate of twist: 1 in 7 inches
    • Forend attachment system: M-LOK

    The Radian Weapons Model 1 .300 AAC Blackout Complete Upper Receiver is designed specifically for suppressed shooting. However, just about everything on this upper is upgraded. But I’ll stick with the suppressor-specific features.

    First, the bolt carrier group is contoured to reduce carrier tilt and weighs slightly more than a standard bolt carrier group to slow your action down. This helps reduce wear on your internal parts. That way your suppressor host lasts just as long as an unsuppressed gun.

    Additionally, the muzzle device is a KeyMount muzzle brake. Right out of the box, this upper is compatible with any suppressor that attaches to a KeyMount muzzle device. So you may not have to worry about buying a suppressor compatible muzzle device.

    Lastly, this upper is made by Radian Weapons, which means you get the Radian Raptor charging handle. If you haven't heard, it’s pretty much the best charging handle you can get.

    Overall, if you’re planning on shooting suppressed, this upper will give you the best performance and component lifespan.


    Putting the Halves Together

    One of the best things about 300 Blackout is that the only difference between a 5.56mm rifle and 300 Blackout rifle is the barrel. So a complete 300 Blackout upper is the most efficient way to shoot both 300 Blackout and 5.56mm.

    Getting the best 300 Blackout upper that you can afford will add a ton of versatility to your gun collection.

    PSA 10.5 Pistol-Length 300AAC

    If you want the best upper for the best price, get the PSA 10.5" Pistol-Length 300AAC. It’s affordable. And this model works great, so long as you make sure there are no assembly issues before you fire it.

    Still shooting exclusively 5.56mm? It’s time to get a 300 Blackout upper and double the number of calibers that you can shoot.