The Best .300 Blackout Uppers

Below is my list of .300 Blackout upper receiver recommendations. I list the best choices in terms of value, performance, design, and cost.

Click on the name to go to the product page, read reviews, and check prices, or skip ahead to the list of uppers.

1. Palmetto State

For pistol uppers, Palmetto State Armory has put together a sweet offering here. This one has a short barrel that leaves plenty of room beyond the handguard for your desired can, making it perfect for home defense or close quarters.

We also love the lightweight handguard, which helps prevent it from getting overly front-heavy when mounted with a suppressor.

That open handguard design, as much as it keeps weight down and helps with thermal performance, may come at the cost of heat transfer to your hands, so think about some gloves when shooting this one.

What we liked:

• Lightweight & great for close quarters
• Heavy profile barrel for sustained fire
• Full auto bolt carrier
• Lifetime warranty

What we didn’t:

• Handguard has a lot of cut-outs & could get warm
• Quality can be a little hit and miss

2. Daniel Defense

Daniel Defense produces some of the best high-speed platforms to more than capable operators – like the U.S. Navy SEALs.

This upper from the folks at Daniel Defense is certainly no exception to their quality. The fit and finish are excellent, and the 10.5-inch barrel is about the perfect length for a .300 BLK pistol. Plus you get all the bells and whistles of a DD upper, including their world-class quad rail handguard.

With the already short length here, the best application for this upper would be to add a short suppressor and use subsonic ammunition. Doing that will let you shoot .300 Blackout indoors without totally ruining your eyes and ears: this makes the DDM4 300s a great entry into this new caliber.

What we liked:

• Standard flash suppressor is quite good
• The rail covers are a nice, quality touch
• Durable chrome-plated bolt carrier group
• World-class quad rail

What we didn’t:

• Expensive

3. Smith & Wesson

Smith and Wesson have been getting into the AR game really seriously in the past ten years, so it’s great to see them selling an upper in .300 Blackout as well. This one is meant for mainly rifle configurations, and we think it would be especially useful as a hunting rifle when paired with a quality suppressor.

One thing we might change out were it our gun is the handguard: it has a ton of room to mount anything up to and including the kitchen sink, but the square profile is kind of thick in the hand.

What we liked:

• 16” option works for rifle or pistol build
• Sized-up muzzle brake works well
• Tons of rail space for accessories
• Threaded barrel

What we didn’t:

• Awkward handguard length

4. CMMG

To round out our picks, we wanted something that would be especially suitable for a pistol build, and the CMMG Resolute is an awesome upper in everything from 6.5″ and up barrel formats.

It comes with a flash hider, but I recommend fitting a suppressor on it, as the length just screams for a can and hand stop. At barrels this short, there is no room for error, so a suppressor paired with a hand stop gives you more stability to work with.

You’ll need to bring your own BCG and charging handle, but for those who know and rely on the CMMG brand and want to keep it short, this is a quality upper.

What we liked:

• 6.5” barrel option is perfect for a pistol build
• Comes with a nice M-LOK handguard
• Standard flash hider isn’t pinned, so you can add a suppressor or muzzle brake
• Really light & slick
• Longer options available from CMMG

What we didn’t:

• Includes a left-hand side charging handle, which alters some people’s build plans

The short, stubby round, the .300 BLK, outperforms the 7.62x39mm at 300 yards. And at close range, the 5.56mm, frankly, is an awful round.

There’s a good reason that Colt made ARs in 9mm going back into the Vietnam era. Indoors and out of short barrels, the 5.56mm makes a ton of noise and even more flash, so it’s really not engineered for CQB or urban combat at all.

Of course, the 9mm approach is only a stopgap measure that lacks stopping power at range. It also requires 9mm-specific components – and you still end up with a sub-par AR full of compromise (or more of a PCC). For military and law-enforcement applications, a .300 Blackout-chambered M4 is a marvelous sub-gun replacement, with a cartridge considerably more effective than a 9mm pistol-caliber MP5.

The same thing can be said for home defense in a .300-chambered AR replacing pistol-caliber carbines – lots more stopping power with little fuss.

In standard 5.56mm, ARs will hit peak burn out of about a 16” barrel, with 14.5” as short as you can go with a 5.56 barrel and still get performant terminal ballistics, complete powder burn, and a lack of a fireball.

Those longer barrels make them more cumbersome when it comes to close-range applications like home defense.

Instead, we want a short-barreled rifle or pistol that, especially when paired with a suppressor or muzzle brake, can lead to a handy and quiet rifle that still makes more impact than a 9mm, and in most cases, more than 5.56mm.

Tests by AAC way back in 2012 (and of course, ballistics have improved since then) demonstrated that the .300 BLK could still be effective out to 440 yards– when fired from a barrel as short as 9 inches, making it ideal for use in AR pistols.

When it comes to a bad-breath-distance engagement, we want a .300 blackout.

In addition to its performance characteristics, one of the major contributors to the .300 Blackout’s popularity is its compatibility with existing 5.56/223 AR-15 rifle components.

Your bolt carrier groups, upper and lower receivers, magazines, rails, and the like work just as well with the .300 BLK as your 5.56 NATO rounds. Plus, a .300 Blackout-chambered AR-15 still uses the same magazines without a loss of capacity; i.e., a 30-round 5.56 NATO AR mag will still hold 30 rounds of Blackout.

Just swap the barrel and gas system and commence pow-pow. Check out our gas system guide for more on that front.

1. The shorter, the better

For the .300 Blackout, shorter is better. The round simply doesn’t perform at range the way a 5.56/223 round does. It’s a heavier, slower-moving round, but thanks to the .30 caliber bore, it will burn its full potential in a 9-inch barrel.

That means that no, you won’t be punching out targets at a mile. But inside of 200 yards, you’ll be hitting well above the weight of a 5.56mm. Want more? Take a deep dive into AR barrels with our barrel guide.

2. Threaded barrels

Because it moves slower, it’s also a lot quieter: this makes .300 Blackout a great choice for a good flash suppressor, a silencer, or a muzzle brake, which requires a threaded barrel.

Shorter barrel lengths are excellent for close-quarters engagements, making a .300 Blackout rifle or pistol a great option for home defense, but you’ll want to protect your hearing with a suppressor or some other muzzle device.

First of all, a little legalese will be necessary here. Since .300 Blackout does best out of shorter barrels, we’ll be recommending AR pistols as final builds.

That means that the lower you put it on has to have been registered as a pistol when it was made, and that you cannot put a stock or a forward pistol grip on it. But we all love a good brace!

3. Muzzle devices

Also, you’ll want to consider what muzzle devices you want to try out. Since we think a high-quality .300 Blackout does so well suppressed, we think a pistol upper with a threaded barrel is the perfect way to get the best out of the round.

A .300 Blackout pistol, with a suppressor, is still only about as long as an average AR-15 without a suppressor, so it ends up being a really handy package overall, which is one of the things that we like about the round.

With that said, all of the options on this list are good, and we think you could make a great pistol or rifle out of any of them. We recommend thinking about the parts you already have and what you want to do with them before making a purchase. With this guide in hand and a little bit of thinking, you’ll be well on your way to an excellent .300 Blackout pistol or rifle.

1. ATF, Firearms Commerce in the United States, 2011, Pg 22
2. American Shooting Journal, .300 BLK vs 5.56
3. Fenix Ammunition, A Ballistic Comparison of 5.56x45mm vs. .300 AAC Blackout
4. Cover photo