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5 Best .300 Blackout AR-15 Uppers

Pair of .300 BLK 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.
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    Updated Feb. 2024: Replaced Radical Firearms upper with Radian Model 1. Updated BRN-180 upper to reflect Gen 2 changes.

    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.

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

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

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

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

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

    THE QUICK LIST

    1. Short Stroke Piston Option

      Brownells BRN-180 Uppers

    Table of Contents

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    How We Chose the Best .300 BLK Uppers

    The entire team at Pew Pew Tactical had a hand in contributing to this post. Our team comprises prior law enforcement, competition shooters, hunters, instructors, and hobbyists who’ve spent extensive hours at the range testing and shooting what we recommend.

    PPT Team Staff
    The Pew Pew Tactical Team

    We constantly test gear and regularly update articles as new models become available, so if you’re favorite isn’t here, check back soon!

    Best .300 Blackout Uppers

    1. Palmetto State Armory

    Most Affordable
    $199
    at Palmetto State Armory

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Pros

    • Large amount of options available
    • Affordable
    • Reliable

    Cons

    • Non-adjustable gas block

    PSA makes a huge range of items for the AR platform.

    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.

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

    PSA 5.56 Uppers
    PSA 5.56 Uppers

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

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

    2. Ballistic Advantage

    $449
    at Ballistic Advantage

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Pros

    • Good performance
    • Solid build quality
    • Reliable

    Cons

    • BCG and CH not included
    • Limited options

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

    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.

    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

    What’s your take on Ballistic Advantage?

    Readers’ Ratings

    4.99/5 (1746)

    Your Rating?

    3. Aero Precision M4E1

    Runner-Up
    $417
    at OpticsPlanet

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Pros

    • Good performance
    • Solid build quality
    • Reliable

    Cons

    • BCG and CH not included

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

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

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

    Aero makes gear that works, and these uppers are perfect for your next .300 BLK build or to convert your 5.56 rifle. Be sure to check out our review of their 5.56 uppers.

    4. Radian Model 1

    Best Overall
    $1,833
    at OpticsPlanet

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Pros

    • Outstanding accuracy
    • Excellent quality control
    • Optimized for suppressor usage

    Cons

    • Expensive

    If you are looking for the best of the best, look no further than the Radian Model 1.

    These uppers are made with ultra high-quality raw materials and constructed with exacting quality control.

    Features include a premium match-grade 416R stainless barrel, nitrided enhanced M16 BCG, Radian Raptor SD suppressor-optimized charging handle, Radian handguard with anti-rotation pins, and your choice of SilencerCo ASR or Dead Air flash hider.

    Radian Model 1 .300 BLK SBR (Photo: Radian Weapons)

    Radian also guarantees sub-moa performance when using Black Hills match-grade ammo.

    While this upper is spendy, the performance and build quality may be enough to justify the cost for some.

    5. Brownells BRN-180 Gen 2

    Short Stroke Piston Option
    $849
    at Brownells

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Pros

    • Bufferless designs allows for folding stocks
    • Easily adjustable gas block
    • Short-stroke piston

    Cons

    • Doesn't use standard AR-15 upper parts

    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.

    BRN-180 Piston Parts
    BRN-180 Piston Parts

    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 that we built for a super nice truck gun.

    BRN-180 .300 BLK Folded
    BRN-180 .300 BLK Folded

    Brownells also now offers a suppressor-optimized version that includes a gas shut-off setting. Combined with an adjustable side-charging handle that can be pivoted downward, this allows you to seamlessly switch between semi-auto and a true “single-shot” bolt-action mode for extreme sound control.

    BRN-180 .300 BLK Pistol with BRN Lower
    BRN-180 .300 BLK Pistol with BRN Lower

    We also combo-ed it with the BRN lower, which gives you Picatinny rails for use with your favorite brace or stock (if you go the SBR route).

    $119
    at Brownells

    Prices accurate at time of writing

    Prices accurate at time of writing

    Available Coupons

    Check out our full review of the 16-inch 5.56 version.

    Why You May Want a .300 Blackout Upper

    The .300 BLK became a behemoth in the industry because of its direct compatibility with existing AR-15 rifles.

    This includes compatibility with standard 5.56 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.

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

    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.”

    .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. 

    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.

    .300 BLK AR-15 Pistols
    .300 BLK AR-15 Pistols

    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. 

    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.

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    45 Leave a Reply

    • Jimmy

      What kind of handguard is that ?

      March 27, 2024 11:23 pm
    • Weston Cecil

      What about Primary Weapons System? Their 300blk is awesome. I run it suppressed and I’ve never had a failure of any kind and with my Sandman S it’s perfectly sized zero gas in my face.

      February 29, 2024 6:57 pm
    • Eric Hung Sucks

      Literally the worst list I’ve ever seen lol. You think that Aero and PSA are making the best .300 BLK uppers?

      July 26, 2023 10:39 am
      • Michael Johnson

        What's wrong with Aero?

        December 7, 2023 2:13 am
    • Sébastien

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

      January 6, 2023 7:44 am
    • 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
      • 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
    • 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
      • 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
      • 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
        • 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
    • 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
      • 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
      • CFT

        Those are Radian Weapons Model 1 AR's.

        August 11, 2022 10:50 am
    • 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
      • 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
    • 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
    • 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
      • David, PPT Editor

        Correct!

        April 9, 2020 6:39 pm
      • Kuzz

        Roger That

        May 10, 2020 6:33 pm
      • Jditty

        Yup. And a 5.56 lower too.

        May 22, 2020 5:11 pm
    • 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
      • 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
      • asdf

        daniel defense

        January 3, 2020 4:16 am
    • 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
    • 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
      • 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
      • 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
    • Michael

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

      May 14, 2019 12:59 am
      • 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
    • 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
    • Frank

      What FDE upper is in the top pic?

      February 11, 2019 8:51 am
    • Frank

      what FDE upper is in the top pic ?

      February 11, 2019 8:50 am
    • 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
    • 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
    • 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
    • Will

      Anyone offering a left-handed 300 AAC upper?

      December 17, 2018 5:45 pm
      • 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
      • Adrian

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

        December 24, 2018 11:44 am
    • 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
    • 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
    • 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
    • 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
    • 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
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