Hand-Picked Daily GUN DEALS, and Exclusive Coupons Codes >>>

5 Best .300 Blackout AR-15 Uppers

The .300 Blackout is here to stay. We'll cover the best uppers out there for all budgets and build types...from pistol to rifle to suppressed.

The AR world is absolutely massive, and you can chamber an AR in everything from .22 LR to .45-70 Government. The AR is often adapted to function in calibers it was never designed for shooting.

Popular Rifle Calibers, Part I
Popular Rifle Calibers, Part I

While that’s cool when it happens, what’s even cooler is when rounds are designed specifically for the AR platform.

.300 BLK 123gr vs 200gr
.300 BLK 123gr vs 200gr

One such round is the .300 Blackout. The .300 BLK has easily been the most successful new caliber in the last 20 years.

Read on to see how to get your standard 5.56 AR-15 ready to use .300 BLK.

Pair of .300 BLK Uppers
Pair of .300 BLK Uppers

Summary of Our Top Picks

  1. Most Affordable

    PSA .300 Blackout Uppers

    PSA does it again with sub-$200 uppers that work.

  2. Editor's Pick

    Ballistic Advantage .300 BLK Uppers

    The 10.3" BA upper is the basis of my truck gun build.

  3. Another Affordable Option

    Radical Firearms .300 AAC Blackout Upper Assembly

    Another affordable option if you have your own BCG or CH.

  4. Short Stroke Piston Option

    Brownells BRN-180 Uppers

    Go the folded brace route with a BRN-180 upper.

Table of Contents

Loading...

Why the .300 Blackout Succeeded

The .300 BLK became a behemoth in the industry because of its direct compatibility with existing AR-15 rifles since it is compatible with almost every standard 5.56/223 AR-15 part.

This includes magazines, bolt carrier groups, upper and lower receivers, rails, buffers, buffer assemblies, stocks, etc. Really, the biggest change is the barrel and the gas system.

Other than that, it’s a standard AR-15.

.300 BLK AR-15 Pistol, 8-Inch Ballistic Advantage
.300 BLK AR-15 Pistol, 9-Inch Ballistic Advantage

This makes it possible to convert your 5.56 AR-15 into a .300 BLK AR-15 with nothing more than a swap of the upper receiver. 

That’s it. 

You can use the same mags, same BCGs, etc.

Why You May Want a .300 Blackout Upper

Besides the easy conversion between 5.56 and .300 BLK, the .300 BLK does a lot the 5.56 can’t.

First off, it’s a very versatile load with projectiles weights ranging from 110 grains to 220 grains. The 110-grain rounds are supersonic, and the 220 subsonic.

.300 BLK 123gr vs 200gr
.300 BLK 123gr vs 200gr

A subsonic round is much easier to suppress and much quieter when suppressed. The .300 BLK also reaches peak ballistic potential from a 9-inch barrel.

Ballistic Advantage .300 BLK Barrels, 9 vs 8 Inch
Ballistic Advantage .300 BLK Barrels, 9 vs. 8 Inch

The 5.56 requires a 20-inch barrel to reach peak ballistic performance.

I won’t dive too deep into the 5.56 vs. .300 Blackout debate because we have an article on that.

.300 BLK vs 7.62x39mm
.300 BLK vs 7.62x39mm

In my opinion, the two rounds are designed for different tasks, and having both simply opens up your options.

What I will do is point you to a few of the best .300 BLK upper receivers so that you can make your transition to this wonder-round.

Best .300 Blackout Barrel Length?

This question comes up a lot…and the answer varies depending on your end use and if you’re using a suppressor.

We asked Clint Hanson, the founder of Ballistic Advantage, and his go-to barrel length is 10. inches for reliability.

The 10.3-inch length is “not too short and not too long from an all-around/fit every human size standpoint” because you have to figure in the handguard and potential suppressor length.

Pair of .300 BLK AR-15s
Pair of .300 BLK AR-15s (10.3″ Top and 9″ Suppressed Bottom)

Once you go under 8 inches or so, you can run into cycling issues since the .300 BLK is a low-pressure round.

So if compactness is the name of the game…make sure you have a suppressor to add some backpressure and also enable you to run a longer handguard.

“Every length has a problem it’s solving, but the 10.3 inch is the go-to and most versatile.”

Best .300 Blackout Uppers

1. Palmetto State Armory

PSA makes a huge range of items for the AR-15 platform and, for that matter, the AR-10 also.

PSA 5.56 Uppers
PSA 5.56 Uppers

One of the many things they cover is the .300 BLK in uppers of all sizes, from 7.5-inch barrels all the way to 16-inch barrels, with every standard size in between.

Most Affordable
199
at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

No matter what kind of .300 BLK build you want to create, you can find the upper for it from PSA.

Short little pistols? Check. SBR? Check. Rifle? Check.

PSA is also, generally, one of the most budget-friendly options.

2. Ballistic Advantage

I love Ballistic Advantage 5.56 barrels (full review) for the right mix of performance and affordability.

Ballistic Advantage Hanson Barrel
Ballistic Advantage Hanson Barrel

This time I checked out both a 9-inch barrel and a complete 10.3-inch BLK upper recommended by Clint Hanson.

Ballistic Advantage .300 BLK Barrels, 10.3 vs 9 Inch
Ballistic Advantage .300 BLK Barrels, 10.3 vs. 9 Inch

I chose the 10.3-inch Hanson barrel factory upper to be my trunk gun, where I valued reliability without needing a suppressor to add back pressure. The length also gave me enough rail real estate to put on lights.

.300 BLK AR-15 Pistol, 10.3-Inch Ballistic Advantage
.300 BLK AR-15 Pistol, 10.3-Inch Ballistic Advantage

I had initial problems with using an upgraded WMD NiB BCG, but once I switched back to a mil-spec BCG it ran everything like a champ.

From steel-cased Wolf range ammo to brass supersonic and 220gr subsonic rounds.

Coupled with a LAW Tactical Folder, it fits nicely into my small trunk safe.

Law Tactical Gen 3 on .300 BLK Pistol
Law Tactical Gen 3 on .300 BLK Pistol
269
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

My editor’s pick recommendation for a do-all .300 BLK upper.

504
at Ballistic Advantage

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

For my suppressed home build, I went with a 9-inch Modern Series barrel for something slightly shorter but still reliable. It’s been flawless with all different types of .300 BLK ammo.

.300 BLK AR-15 Pistol, 9-Inch Ballistic Advantage
.300 BLK AR-15 Pistol, 9-Inch Ballistic Advantage

Check out all the .300 BLK Complete uppers here or just the barrels if you’re looking to build your own.

Available Coupons

What’s your take on BA?

Readers' Ratings

4.99/5 (1087)

Your Rating?

3. Aero Precision M4E1

Aero Precision is one of the best companies out there for modern, high-quality AR components. 

Aero AR-15 10.5" Pistol
Aero AR-15 10.5″ Pistol

The M4E1 in .300 BLK comes available in 8-, 10-, and 16-inch barreled options.

Runner-Up
475
at Aero Precision

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

A 10-inch barrel on an AR pistol or a short-barreled rifle is perfect for the .300 BLK. The uppers all feature different-length handguards that accommodate the mounted flash suppressor.

Aero makes gear that works, and these uppers are perfect for your next .300 BLK build or to convert your 5.56 rifle. We also love their 5.56 uppers – check out the review.

Aero Precision M4E1 with ATLAS Handguards
Aero Precision M4E1 with ATLAS Handguards

4. Radical Firearms .300 Blackout Uppers

We all have a budget to live and die by, and recognizing that, I’d suggest any of the .300 BLK options from Radical firearms. 

These budget-priced uppers lack a BCG and charging handle, but they’ll take any standard AR BCG and charging handle.

Another Affordable Option
225
at OpticsPlanet

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

These uppers range from 8.5-inch barrels to 16-inch options. Radical firearms also produce their uppers in a wide variety of configurations.

These uppers aren’t the fanciest, but they work. 

They are mil-spec, and all feature flat top uppers, forwards assists, and threaded barrels. Prices range, but each option is affordable and thoroughly modern.

My personal favorite is the 8.5-inch upper with an MLOK rail. It’s short and sweet and perfect for a .300 BLK pistol or SBR. The M-LOK rail is fantastic and provides more than enough room for accessory attachment.

5. Brownells BRN-180

Want to go a little different? Enter the BRN series, which is based on the AR-180 series that didn’t have a buffer tube but instead went with a short-stroke piston.

Check out our full review of the 16″ 5.56 version.

BRN-180 Fighting Rifle and Kit
BRN-180 Fighting Rifle and Kit

That means if you went with an under 16-inch barrel (which you pretty much gotta do with a .300 BLK), then you can get a folding brace for a super compact AR.

My choice is the 10-inch .300 BLK upper.

Short Stroke Piston Option
900
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

And be sure to snag a bufferless Picatinny end lower receiver.

169
at Brownells

Prices accurate at time of writing

Prices accurate at time of writing

Available Coupons

.300 Blackout Safety

I do want to note one thing before you run out and get a new .300 BLK upper – you NEED to be careful when switching between uppers or even when you have a dedicated .300 BLK rifle and a 5.56 rifle. 

You see, .300 BLK can chamber in most 5.56 barrels; however, if you try to shoot it – your barrel (and sometimes more) will literally burst. 

Explosively.

This used to be a rifle. Used to be.
This used to be a 5.56 rifle until the owner loaded .300 BLK into it and pulled the trigger. Used to be.

As you can see in the image above, bad things can happen when you load the wrong cartridge into your rifle.

Make sure you keep ammo and mags separate.

Personally, I keep them organized by using different color mags – FDE and black for 5.56 and Olive Drab for .300 BLK. I also double and triple-check things before loading a mag into the rifle.

Final Thoughts

With suppressors and SBRs being all the rage, the .300 BLK continues to grow. The ammo price continues to drop, and upper receiver options are everywhere.

Pair of .300 BLK Uppers
Pair of .300 BLK Uppers

These are just my favorites and represent a very small section of the market. I’m one man and couldn’t possibly see each and every upper out there. Knowing the industry, there must be some amazing options on the market I simply haven’t seen. 

Check out more calibers and everything AR in the Ultimate AR-15 Resource.

What are your favorite .300 BLK upper receivers? Anything that makes them stand out? Need a dedicated optic for the .300 BLK drops? Check out our Best .300 BLK Scopes & Optics.

The Best Gun Deals, Coupons and Finds

Subscribe to Pew Pew Tactical's sales and deals email.

41 Leave a Reply

  • Commenter Avatar
    Sébastien

    300 HAM'R leads the way. It's everything 300 Blackout supersonic wishes it was.

    January 6, 2023 7:44 am
  • Commenter Avatar
    Eddie

    Anyone have a top 5 recommended, 300 blackout stripped upper with the focus being lightweight and gas reducing? This would be for an 8" barrel.

    July 20, 2022 5:48 am
    • Commenter Avatar
      Afro

      To keep gas out of your face, you may want to choose one of the new flow-through, 3d printed suppressors from OSS/HuxWrx. Sig is attaching these to the new Army rifles running 6.5. However, subsonic 300blk tends to be pretty good about letting the operator breathe, depending on manufacturer. I'd also recommend going a little longer, ideal length for gas burn is 9", so 10 or 10.5" are perfect, and that keeps gas out of your face too.

      Any ole 300blk pistol upper from PSA at that length will work just fine. If you want to get a little pickier, go with an adjustable gas block or one that's long enough to allow you to slide an adjustable gas gadget under the hand guard and that pokes out a little to let you adjust it. It may be on the heavier side because they like heavy barrel profiles, but there's Faxon with a pencil barrel if you want it to lose weight.

      August 21, 2022 1:58 pm
  • Commenter Avatar
    Jon Horton

    I have recently joined an Anderson lower with a upper receiver that I got from Bear Creek armory for something around $200. It carries a silencer central can and my property is super densely forested very few clear long shots so this is absolutely perfect for me. Just make sure and meet ATF's guidelines for AR-15 pistols. A 10 and 1/2 in barrel is okay.

    August 16, 2021 7:11 am
    • Commenter Avatar
      Shane

      The only key here with ATF's standards is a collapsible brace that maxes out at 14" from end to trigger face. Otherwise barrel length doesn't matter, when you start with a "pistol lower" kit.

      August 21, 2022 2:00 pm
    • Commenter Avatar
      Chris

      Pretty old article, all of the mentions of keymod give it away, as the industry has moved to the magpul standard m-lok. Can we get an updated for 2022 article? 300 seems to be heating up again and with the eform form 4, suppressors (and calibers that are easily suppressed) are also popular.

      August 21, 2022 2:03 pm
      • Commenter Avatar
        Jacki Billings

        Hey Chris, we're slowly making our way through updates on older articles. But I will make sure to put this on the list to get to it sooner rather than later. Thanks!

        August 22, 2022 5:29 am
  • Commenter Avatar
    Patrick

    Please tell me the make and name of the two AR-15 300 blackouts shown in the picture with the description "Suppressed .300 Blackout"

    I like the way these two set ups look.

    Please send me the specs (including the name of the suppressors)

    January 26, 2021 12:24 pm
    • Commenter Avatar
      David, PPT Editor

      We found the image on the Wilson Combat website several years ago, they do not seem to be available anymore. I have no information on the specs, sorry.

      January 26, 2021 12:39 pm
    • Commenter Avatar
      CFT

      Those are Radian Weapons Model 1 AR's.

      August 11, 2022 10:50 am
  • Commenter Avatar
    Kuzz

    I have a Radial 8.5" 300blk and it is a nice tight fit on a Areo M4E1 (No need for tension set screw) It shoots straight out to 50yds/ 1.5" group free standing, bench rest 100yds / 3.5" group but I blame the shooter. That is far as train with a 8.5" it is a CQB set up. Headspaced checked out good. People talk down about Radial like they are junk. News people Radial pistol uppers are good to go for what they are designed to do. The only down side would be the barrels are 4140 so I would guess they won't hold up to high round counts. But at their price point I can buy a complete upper for the cost of a barrel from other name brands.

    May 10, 2020 6:59 pm
    • Commenter Avatar
      Matthew Robert Davis

      My first ar 15 was on of their rf15. And its held up great. My only issue is with the buffer tube and and exploding gas tube but both are my fault.

      July 26, 2021 6:40 pm
  • Commenter Avatar
    Colton

    This list definitely should be updated to include gas piston systems. Primary Weapons Systems sells a complete upper exclusive on Brownells that is competitively priced compared to the others on this list, but you get a far superior action. The model is MK1 Pro.

    May 1, 2020 10:48 am
  • Commenter Avatar
    Conroy

    So what I'm gathering from this is, I can use a 5.56 BCG as well as a charging handle in a .300 blackout upper, correct?

    April 9, 2020 5:56 pm
    • Commenter Avatar
      David, PPT Editor

      Correct!

      April 9, 2020 6:39 pm
    • Commenter Avatar
      Kuzz

      Roger That

      May 10, 2020 6:33 pm
    • Commenter Avatar
      Jditty

      Yup. And a 5.56 lower too.

      May 22, 2020 5:11 pm
  • Commenter Avatar
    Chris

    Interested in a one-stamp, integrally-suppressed blackout upper. Any u guys can recommend or recommend staying away from? Thx!

    December 22, 2019 5:39 pm
    • Commenter Avatar
      KMPLSV

      here's just what you're lookin' for bud....

      http://www.pewpewtactical.com/go/aero/aero-precision-300-blk-upper/

      December 27, 2019 11:14 am
    • Commenter Avatar
      asdf

      daniel defense

      January 3, 2020 4:16 am
  • Commenter Avatar
    D. Bonnichsen

    No DDM4 300S?? I have one of these and wouldn’t think twice about buying it again. Only drawback is they force you to buy a BCG and charging handle with an upper only purchase...since I already own a DDM4 V7 Pro I didn’t much like having to pay the extra money for what I already owned.

    November 25, 2019 9:17 am
  • Commenter Avatar
    charles sacco

    I saw the 300BLK fire from the 5.56 chamber rife, What would happen if you fire a 5.56 from a 300BLK rife

    October 19, 2019 7:19 am
    • Commenter Avatar
      L.jones

      Catastrophic failure!!! That is what will happen!!! You can use the 5.56/233mags with the 300blk and the bcg, but that's it, so eaither buy a upper chambered in 300blk or swap barrels.

      October 20, 2019 6:42 pm
    • Commenter Avatar
      tom ochs

      shooting 5.56 in a 300blk will not explode - but your guess is as good as mine where the bullet goes . . . if it doesn't engage the rifling it doesn't fly straight

      November 27, 2019 7:37 am
  • Commenter Avatar
    Michael

    What handguard/upper is the bottom most picture with the 2 rifles?

    May 14, 2019 12:59 am
    • Commenter Avatar
      David, PPT Editor

      Both rifles are Wilson Combat, I'm not sure if those exact ones are still made though.

      May 14, 2019 1:42 am
  • Commenter Avatar
    Bud Jameson

    Have been looking at all the AR variations and would like your thoughts/advice on a particular package I'd like to build - .300BO, 16" 1:8 barrel, gas piston, and side-charging upper. Is this doable without special gunsmithing? If so, any recommemdations on the best components?

    April 14, 2019 12:34 pm
  • Commenter Avatar
    Frank

    What FDE upper is in the top pic?

    February 11, 2019 8:51 am
  • Commenter Avatar
    Frank

    what FDE upper is in the top pic ?

    February 11, 2019 8:50 am
  • Commenter Avatar
    Chris L

    I agree extreme care and good organization are a necessity when dealing with uppers in multiple callibers ... but a .308 chambering in a .224 ? I haven't tried it, but it seems implausable.

    January 26, 2019 10:28 am
  • Commenter Avatar
    Chris L

    Enjoying your AR reviews. May I suggest: reviews of side-charge-handle AR uppers. Much more ergonomic for target shooting and hunting - anything from sitting or prone positions. Plus ... no nose bleeds from slapping yourself in the face when your hand slips.

    January 26, 2019 7:42 am
  • Commenter Avatar
    J.D. Echols

    I have purchased a couple of .300 blackout upper receivers from MAS Defense. One pistol and one rifle. I have to say that I am impressed with the quality of their products. The pistol upper has a 10.5" barrell with a 12.62" free float hand guard. There is a flash can tucked neatly inside the handguard. This pistol runs flawlessly. Same story with my 16" rifle. I haven't had any issues with the 416 stainless barrel. Awesome products by an awesome seller. Check them out!

    December 19, 2018 11:05 pm
  • Commenter Avatar
    Will

    Anyone offering a left-handed 300 AAC upper?

    December 17, 2018 5:45 pm
    • Commenter Avatar
      David, PPT Editor

      I haven't seen any, sorry. I suspect the market for that is just too low.

      December 18, 2018 1:47 pm
    • Commenter Avatar
      Adrian

      Stag Arms may . I have one of their left handed ARs.

      December 24, 2018 11:44 am
  • Commenter Avatar
    J. Shores

    I just built a Classic Firearms (Bear Creek Arsenal) .300blk 16" stainless barrel with an Anderson upper. Very accurate and pretty cheap. That is my two cents. I would do it again the same way if I did it again.

    September 15, 2018 9:02 pm
  • Commenter Avatar
    Jim B.

    I built mine from Anderson Mfg. upper and lower at a price cheaper than any previous AR Build...very satisfied with the quality of each component.

    March 30, 2018 12:11 am
  • Commenter Avatar
    Monte Walsh

    I built a .300 in a A2 dissipator configuration, using a pistol length gas system. A2 receiver and stock. Very smooth and the accuracy is excellent with just irons.
    As usual, great article.

    March 29, 2018 5:51 pm
  • Commenter Avatar
    DoubleH

    I bought the 8.5" Radical Arms upper for my SBR. I chose it both for price and the handguard was the 1.5 inch slick tube. On a DD lower this thing is GREAT. With YHM Phantom flash adapter and suppressor all you hear is the bullet hitting the berm. Great investment all around!

    March 29, 2018 4:55 pm
  • Commenter Avatar
    William West

    My wife purchased a bear creek Arsenal .300 blk for my 36th birthday this past December 14. I was elated!! I’ve added upgrades and she’s never failed me not once. I noticed that the rifle feeds better using tapco magazines but I’ve had some success with my hexmags as well. I run Remington umc in both 120 and 220. The rifle performance is amazing. No failures of any kind. I pick up boxes of 20 at Walmart for 15$ and some change. Can’t beat it. I made some half inch thick targets of steel at varying design and man the rifle makes em sing!!

    March 29, 2018 4:47 pm
Join the community! Log in
Please provide a valid email address.
Password is required.
or
Register
Please provide a valid display name.
Please provide a valid email address.
The password should contain at least 8 characters with at least one number or special character.
Please accept in order to continue.
or
Trouble logging in?
Type your email address and we’ll send you a link to reset your password.
Please provide a valid email.
Password
Type your new password and hit button below to confirm it.
Field is required.
Account already exists
We already have an account registered for email address () which is linked to your Facebook account.
To log in type your Pew Pew Meter password below.
Field is required.
Account already exists
We noticed that you have previously logged in with your Account which is linked to the same email address () - we can link both of your accounts together.
In order to link your accounts, hit button below and log in to your Account with the same email as above.

Account in Pew Pew Meter means more

Check what do you get by creating an account
Check and save your reviews!
Bookmark and compare your favorite firearms
Manage your newsletter subscription
pew pew tactical logo

new here?

Personalize your experience.
Select what level shooter you are!

pew pew tactical logo

level up your gun knowledge

Thanks! We'll send you the latest guides and training tips geared towards your level.

pew pew tactical logo

welcome!

You'll now receive newsletters of our best articles on techniques, guns & gear.

$47 value

yours free!

targets targets
free

practice targets

printer icon printable

our 9 favorite targets and drills

free

practice targets

printer icon printable

enter your email to download

We'll only use the information provided according to our privacy policy.

success icon

Ready to Download

Click below to begin your download

download pdf