Are you in the market for a new upper receiver for your .300 Blackout AR-15? If so, you have come to the right place.
Best Compact Upper Receiver: PSA 8.5” .300 Blackout Complete Upper Receiver
If you want a pistol-length .300 AAC AR-15, then take a close look at the PSA 8.5” .300 Blackout Complete Upper Receiver. This upper receiver comes built out of aircraft graded aluminum that is both highly durable and very lightweight, and the barrel is designed to optimize the performance of supersonic .300 Blackout rounds.
Best Upper Receiver Kit: PSA 10.5” .300 Blackout Complete Upper Receiver Kit
If you want to build your own complete .300 AAC AR-15, you should give the PSA 10.5” .300 Blackout Complete Upper Receiver Kit a close look. All you will need to purchase separately is a stripped lower, because besides the complete upper receiver this also ships with all of the components that you will need for your lower .300 BLK receiver as well. All in all, this is an excellent value.
Best Carbine Length Upper Receiver: PSA 16” .300 Blackout Upper Receiver
Finally, if you want a carbine length upper receiver for your .300 Blackout you would be very hard pressed to ignore the PSA 16” .300 Blackout. With a 7075-T6 aluminum construction for the receiver itself and a 41450V chrome vanadium barrel, this upper comes ready to use and install right out of the box and is sure to provide a lifetime of service.
Best Overall Upper Receiver: Primary Weapons MK109 Pro Complete Upper Receiver
The Primary Weapons MK109 Pro Complete Upper Receiver comes ready to go right out of the box. Built out of 7075-T6 aluminum with a black anodized finish, it also comes with features such as an adjustable gas system, Radian Weapons charging handle, and a free floating M-LOK handguard.
The .300 Blackout is an excellent round that is also very versatile. It was originally introduced to help bring an AR-15 subsonic capabilities. And thanks to its good ballistics, the .300 Blackout is an excellent round for hunting game such as deer or boar, and at longer ranges than what the 5.56 is capable of.
What’s more, is that switching your existing 5.56 AR-15 to a .300 Blackout AR-15 is incredibly easy, and all you will need to do is swap out the barrel and the upper receiver. This means that you could keep your existing lower receiver for both calibers.
In this article, we will dive into the merits of the .300 Blackout round and why you should consider it, the top qualities to look for in a new upper receiver for your AR-15, and then our choices for the top three best .300 Blackout upper receivers that you can purchase today.
Why Go With .300 Blackout Round?
The .300 Blackout, which is also known as the .300 AAC, is only one of many different rounds for the AR-15. It’s also one of many rounds that was designed to enhance the performance of the AR-15 over its standard calibers the 5.56 and the .223, which is why that many people may confuse it with 6.5 Grendel or 6.8 SPC.
The main logic behind developing the .300 Blackout was to give a soldier armed with the AR-15 subsonic capabilities. Most US soldiers issued submachine guns in the 9mm caliber were issued these weapons in order to have a quieter weapon than a 5.56 with a silencer.
But with the .300 Blackout, a round that offers subsonic capabilities, the same soldiers could now use their existing M4 carbines with shorter barrels and without having to use a pistol caliber weapon such as the HK MP5. While submachine guns such as the MP5 are certainly compact and easy to maneuver around, they also fire pistol caliber rounds that are not nearly as powerful as rifle rounds.
With the .300 Blackout, soldiers could still use their 6 inch to 9 inch barreled M4s in a tactical setting and with suppressors, but without sacrificing stopping power. All you need to switch an M4 or AR-15 from a 5.56 to .300 Blackout is a new .300 Blackout barrel and certain upper receiver components.
Simply put, the .300 Blackout is one of the best rounds to use in an AR-15 in conjunction with a silencer, and it will create greatly reduced noise than a 5.56 or .223 round. Recoil is also greatly reduced, and when shooting the .300 Blackout, the kick and noise should be more similar to a .22 LR than to an actual 5.56.
What Does The Upper Receiver Do?
Every AR-15 can be basically field stripped into two parts: the upper receiver and the lower receiver. The upper receiver consists of the barrel, the bolt carrier group, hand guards, and the rail system, among other parts.
The upper receiver can therefore easily swap out calibers between the same AR-15. For example, you can use an AR-15 lower for multiple different calibers, and then just install a new upper receiver depending upon the caliber that you are using. This makes it much more affordable to alternate between calibers versus purchasing an entirely new rifle or carbine.
There are many reasons to upgrade your upper receiver from the one that shipped to you out of the factory. An upper receiver is arguably the part of the gun that impacts accuracy the most, specifically if it comes with a free floating hand guard. If your existing upper receiver is not free floating, you should absolutely upgrade to one that is, because your rifle could potentially become up to 50% more accurate.
Another reason you may want to upgrade your upper receiver is if your existing one does not come with all of the features that you need. Budget upper receivers, for instance, often work well enough but also come with lower quality bolt carrier groups, and also sometimes lack a dust cover or a forward assist. And while neither a dust cover nor forward assist are truly necessary for an AR-15 to work, they can both help out greatly with reliability in bad conditions.
Finally, the other reason to upgrade your upper receiver is if you want it to match better with your lower receiver. It’s a good idea for both your upper and your lower to come built out of the same materials and to have the same finish in order to ensure consistency. We’ll discuss the specific materials and finishes that you should look at getting in the next section:
Buyer’s Guide For A .300 Blackout AR-15 Upper Receiver
These are the most important factors to consider when looking for a new upper receiver for your .300 Blackout AR-15:
Should You Get Stripped or Complete?
When purchasing an upper receiver for any AR-15 regardless of caliber, you will need to make a decision between getting a stripped upper receiver or a complete one. A stripped upper receiver means that the receiver is not ready to use out of the box and is missing some components that you will need to add on yourself. The specific stripped upper receivers that you see available on the market can vary greatly in terms of what precisely they are missing.
Complete upper receivers, on the other hand, come ready to go out of the box because they have everything already installed in them. In other words, if you purchase a complete upper along with a complete lower separately, you can put them together and you should have a fully functioning rifle or carbine ready to go.
There’s nothing wrong with getting either a stripped or a complete upper receiver either. If you want to keep things as simple as possible and want an upper that’s ready to go while accepting that you won’t be able to customize it (unless if you were to remove existing components), then you should get a complete upper. But if you want an upper receiver that you can truly customize to your own specifications by adding each of the components separately, you should go with a stripped receiver.
Durability and Corrosion Resistance
Your upper receiver is literally half of the firearm and includes the barrel. For this reason, it simply needs to be as durable as possible. The best materials to go with for an upper receiver for your AR-15 will be made out of 7075-T6 aluminum. This is an aircraft grade aluminum that is both highly durable and also lightweight. For reference, the Beretta 92FS 9mm service pistol is made out of the same materials.
When it comes to finishing to make your firearm more corrosion resistant to rain and moisture, you have options. A nitride finish is one option, and another is to go with a blackened hard coat anodized finish. Both of these are very rust resistant and should serve you well. They also add durability to the aluminum.
Make Sure It Has a Rail
If your upper receiver has a Picatinny rail on the top, it will be very easy for you to add sights, lasers, red dot sights, or scopes. Many upper receivers do not come with sights installed (including complete uppers), so you will need to purchase these separately and then add them to your rail.
It Should Come With A Dust Cover and Forward Assist
As noted previously, neither a dust cover nor forwards assist are truly necessary for an AR-15 to work, but they can also greatly enhanced reliability in rough conditions. The dust cover is designed to keep the elements out of your chamber before firing, and the forward assist is designed to help clear a malfunction.
So long as you’re going to invest money into a new upper receiver, it should come with both the cover and the assist, as both will be nice features to have when you need them.
The 3 Best .300 Blackout Upper Receivers For 2020
Now that we’ve covered why you need to upgrade your .300 Blackout upper receiver and the top qualities to look for, here are our top three choices for a .300 Blackout upper receiver for 2020:
PSA 16” .300 Blackout Upper Receiver
The PSA 16” .300 Blackout Upper Receiver is a good choice for an upper if you want a carbine-length upper receiver. It’s built out of 7075 T6 aluminum and has an M4-type design complete with a .300 Blackout bolt carrier group, forward assist, hand guard, and a barrel. The bolt carrier group is built out of 158 carpenter steel and is built very ruggedly with a fully automatic profile (even though it is only capable of semi-automatic firing in its existing configuration). The entire upper is also coated in nitride for added rust and corrosion resistance. The pistol length gas block is very ideal for the .300 Blackout round as well.
The barrel of the PSA is built out of a chrome moly vanadium 4150V, which is also very durable and ideal for the .300 Blackout. The 1:8 twist rate on the inside of the barrel can easily handle both supersonic and subsonic rounds. The barrel is also of the heavy profile variety, which means that it can shoot through several magazines worth of ammunition without overheating or running into any other issues. As with the rest of the upper, the barrel comes with a nitride finish for excellent rust resistance as well. The end of the barrel also comes equipped with 5/8-24 threads, which means that it can easily accept most muzzle brakes and suppressors.
Finally, this upper receiver from PSA also comes with an A2 flash hider on the end, a Picatinny rail, 15 inch M-Lok rail, and a free floating hand guard. The 16 inch barrel offers a solid compromise between the longer 20 inch barrels and the shorter pistol lengths.
Overall, the PSA .300 Blackout 16” Upper Receiver is a solid choice if you want a carbine-length upper. It’s durable, has a solid chrome moly vanadium barrel, and has. A durable and yet lightweight construction. It does not come with sights, however, so you will need to add those yourself.
- Durable construction from 7075 T6 aluminum
- Complete upper receiver, so it’s ready to go out of the box
- Comes with a free floating hand guard
- Barrel is made out of 4150V chrome moly vanadium
- 1:8 twist rate of the barrel is ideal for .300 Blackout
- Does not come with sights
PSA 8.5” .300 Blackout Complete Upper Receiver
The PSA 8.5” .300 Blackout is another solid upper receiver if you are looking for a compact pistol length option. While an upper receiver this compact would not be a good choice for hunting or long distance precision shooting, it would be a superb choice for tactical use for hunting because of the fact that it’s much more maneuverable in tight conditions.
The receiver itself is built out of 7075-T6 aluminum and has been hard coat anodized to make it as wear and tear resistant as possible. The barrel is designed to handle supersonic rounds with excellent precision and comes with a nitride finish for superior corrosion resistance as well. The bolt carrier group has a fully automatic profile for better corrosion resistance and is built out of 158 Carpenter steel.
Meanwhile, the M-Lok handguard on the upper receiver makes it easy for you to add slings and other compatible accessories as well.
Overall, the PSA 8.5” .300 Blackout Upper Receiver is a solid choice for a pistol-length AR-15. You can mount it on both a pistol lower or a regular rifle lower, and it comes with a durable aluminum build with nice anodized finish for excellent rust resistance. The barrel itself is designed to easily handle supersonic rounds with the utmost precision
- Compact and easily maneuverable
- 1:7 twist rate
- Comes with a full length rail
- Hard coat anodized finish is very rust resistant
- Comes with M-Lok hand guards
- Compact and easily maneuverable in tight conditions
- Barrel is designed to handle supersonic rounds
- Not good for long distance shooting
- Cannot be easily customized
PSA 10.5” .300 Blackout Complete Upper Receiver Kit
This is not just a PSA 10.5” .300 Blackout Upper Receiver, it’s also an entire kit. Not only do you get the upper receiver, but you also get everything else that you will need to complete building the weapon, with the exception the lower receiver that you will need to acquire separately.
This upper receiver features a pistol length gas system. It has an A2 profile barrel, and the interior of the barrel features a 1:8 twist rate that is considered to be optimal for the .300 Blackout round. The receiver is built out of forged aluminum and has a 12-inch M-LOK hand guard installed over it.
The barrel of the muzzle features 5/8-24 inch thread that makes it easy to add suppressors and muzzle brakes. Meanwhile, the lower parts kit includes a pistol grip, buffer tube, fixed stock, and other components.
This kit will complete your rifle for you, and all you will need to acquire is a stripped lower receiver that is compatible with a .300 Blackout upper. Built out of forged aluminum and designed to optimize the .300 Blackout round, this upper comes with almost everything you need to build your own .300 AAC pistol-length AR-15.
- Very compact
- Comes with a full assembly kit (all you need to buy is a stripped lower receiver)
- Compact and very maneuverable
- Trigger is a little bit heavy
Primary Weapons MK109 Pro Complete Upper Receiver
The Primary Weapons MK109 Pro is a complete upper receiver that comes ready to install with a .300 Blackout lower right out of the box.
This receiver comes with a free-floating M-LOK handguard and a short 9.75 inch barrel with a 1:8 twist rate. It also has an adjustable gas system and has a Radian Weapons Raptor charging handle installed. It does not come with sights, so you’ll need to add those yourself. Fortunately, the MK109 has a Picatinny rail over the top of the receiver that makes it easy to add sights, lasers, optics, and other accessories.
The receiver to the MK109 Pro itself is built out of 7075-T6 aluminum and has a blackened anodized finish, which means it can hold up well from rain, snow, or moisture. The total weight of the MK109 is just over three and a half pounds, which makes it a very lightweight option as well.
If you are looking for a solid complete .300 AAC upper receiver that is built out of the highest quality components, you’ll want to check out the MK109 Pro. This complete upper receiver comes with excellent features including an adjustable gas system, free floating handguard, Radian Weapons charging handle, and a durable aluminum build construction.
- Has a 1:8 twist rate
- Comes complete and ready to go right out of the box
- Comes with a long stroke system
- Has a free floating handguard
- Gas system is adjustable
- Radian Weapons Raptor charging handle
- Built out of 7075-T6 aluminum with anodized finish
- Very expensive
- Does not come with sights
And that concludes our list of the top three best .300 Blackout upper receivers for 2020. The .300 Blackout truly is an underrated round that can greatly increase the power and potential of your AR-15. And remember, you can keep your existing 5.56 lower so long as you use a .300 Blackout upper and barrel.
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