You can chamber an AR from.22LR up to.4570 Government. It is not uncommon for the AR to be adapted in order to shoot calibers that it was never intended to fire.
It’s great when that happens, but it’s even better when the rounds are specifically created for the AR platform.
The.300 Blackout is one such round. The.300 BLK is the most popular new caliber of the past 20 years.
Learn how to convert your 5.56 AR-15 to.300 Black.
How we selected the best.300 BLK uppers
This post was written by the entire Pew Pew Tactical team. Our team includes former law enforcement, competition shooting, hunters, instructors and hobbyists. They’ve spent countless hours on the range testing what we recommend.
Check back often if your favorite gear isn’t listed. We’re always testing new gear and updating articles to reflect the latest models.
Best.300 Blackout Uppers
1. Palmetto State Armory
PSA produces a wide range of AR-compatible items.
They cover the.300 BLK uppers in all sizes. From 7.5-inch barrels to 16-inch, they have every size standard.
You can choose the right upper from PSA for any.300 BLK build.
Short little pistols? Check. SBR? Check. Rifle? Check.
PSA is one of the most affordable options.
2. Ballistic Advantage
Ballistic Advantage 5.56 barrels are the best for a combination of performance and affordability.
This time, I looked at both a 9.3-inch barrel as well as a 10.3-inch complete BLK upper that Clint Hanson recommended.
I selected the factory upper with a 10.3-inch Hanson barriquet as my trunk gun because I wanted reliability without having to use a suppressor. I also had enough rail space to mount lights.
The upgraded WMD NiB BCG caused me some initial issues, but when I switched to a standard mil-spec BCG everything worked perfectly — from the steel-cased Wolf Range ammo up to the brass supersonics and 220gr Subsonic rounds.
I chose a 9-inch Modern Series for my home suppressed build because it was shorter, but still reliable. It has been flawless when using all types of.300 Blackout ammo.
3. Aero Precision M4E1
Aero Precision is a leading manufacturer of high-quality, modern AR components.
The M4E1 is available with 8, 10 and 16-inch barrels.
The.300 BLK is best suited to an AR pistol with a 10-inch barrel or a short-barreled AR rifle. All uppers feature handguards of different lengths to accommodate the flash suppressor.
Aero produces quality gear, and these uppers will work for your next 5.56 build or.300 BLK conversion.
4. Radian Model 1
Radian Model 1 is the ultimate in quality.
The uppers are constructed using only the highest quality raw materials.
The features include a match-grade stainless 416R barrel, an enhanced M16 BCG with nitriding, Radian Raptor SD charging handle optimized for suppressors, Radian handguards with anti-rotational pins and your choice between SilencerCo’s ASR or Dead Air Flash Hider.
Radian guarantees submoa performance with Black Hills match grade ammo.
This upper may seem expensive, but the build quality and performance could be worth it for some.
5. Brownells BRN-180 Gen 2
Do you want to try something different? The BRN series is based on AR-180, but it doesn’t use a buffer tube. Instead, it uses a piston with a shorter stroke.
If you have a barrel under 16 inches (which is what you’ll need for the.300 BLK), you can buy a folding brace to make your AR super compact.
Brownnells offers a suppressor optimized version with a gas shut off setting. This allows for a seamless switch between a semi-auto mode and’single shot’ bolt-action mode.
If you choose the SBR route, you can also combine it with the BRN Lower which provides Picatinny Rails to use with your brace of choice or stock.
Why You Might Want a Blackout Upper.300
The.300 BLK was a huge success in the industry due to its compatibility with AR-15 rifles.
Compatibility with 5.56 standard magazines, upper and lower receivers as well as buffer assemblies, stocks and buffer assemblies is also included. The barrel and gas system are the two biggest changes.
The.300 Black can do a lot more than the 5.56.
It’s also a versatile load, with projectile weights that range from 110 to 220 grams . The 220 grain rounds are subsonic and the 110 grain rounds supersonic.
Subsonic rounds are much easier to suppress, and they also sound much quieter. A 9-inch barrel also allows the.300 BLK to reach its maximum ballistic potential.
To achieve maximum ballistic performance, the 5.56 needs a barrel of 20 inches.
We have an article that discusses the debate between 5.56 and.300 Blackout.
I think the two rounds were designed to accomplish different tasks and that having both just gives you more options.
You will find a list of some of the best upper receivers for.300 BLK so you can easily make the switch to this wonderful round.
What is the best.300 blackout barrel length?
This question is asked a lot…and it depends on the end use of your suppressor and whether you are using one.
The founder of Ballistic Advantage Clint Hanson told us that his preferred barrel length for reliability is 10 inches.
Because you need to factor in the suppressor and handguard length, 10.3 inches is “not too long and not too short from an all-around/fits every human size perspective”.
If you are shooting a.300 BLK round, which is low pressure, and you get below 8 inches you may have some cycling problems.
If compactness is your goal, you should consider a suppressor that will add backpressure to the weapon and allow you to use a longer handguard.
Every length solves a different problem, but 10.3 inches is the most versatile and the best-selling.
Blackout Safety.300
Before you rush out to buy a new upper for.300 Black, you MUST be careful when changing uppers. This is true even if you own a.300 Black rifle and a 5.56 gun.
The.300 BLK cartridge can fit in many 5.56 barrels, but if you shoot it, your barrel will literally burst.
You can see from the picture above that bad things can happen if you put the wrong cartridge in your rifle. Separate your ammo from magazines.
For me, I organize them by using different colored magazines – Olive Drab and FDE for.300 BLK and Black and Black for 5.56. Also, I double- and triple check things before loading the mags into the rifle.
Final Thoughts
The.300 BLK is growing in popularity as suppressors, SBRs and other accessories become more popular. Ammo prices continue to fall, and there are many upper receiver options.
These are my favorite products and only represent a small part of the market. I am only one person and could not possibly have seen every upper available. Knowing the industry I’m sure there are some incredible options out there that I haven’t seen.
What are some of your favorite.300 Black upper receivers? What makes them unique? Do you need a dedicated optic to shoot.300 BLK? Browse our best.300 BLK Scopes & Optics.
