The .300 BLK offers a lot of performance attributes that are relatively lacking in 5.56 and .223. For instance, the .300 BLK offers greater stopping power and performs better from a shorter barrel than either of these alternatives, despite the fact that they are more common.
That being the case, if you are considering building another AR, here are some things you should keep in mind if you build with a .300 BLK upper.
A Shorter Upper Is a Good Bet
If you’re building with a .300 BLK upper, shorter is a really good bet for this cartridge, and for two reasons. For those of you that are interested in building with a .300 Blackout upper, 5 inches can be a good size.
Here’s why: one, a longer barrel is a waste here, just because there’s no point. This cartridge does not perform well at longer ranges, so there’s just no reason to add that weight and barrel length. You need it with 5.56 and other fast, flat-shooting cartridges, but you don’t need it here.
The other thing is that .300 BLK performs very well from short barrels. In fact, if you have a .300 Blackout upper, 5 inches is all you need. Whereas other cartridges won’t experience complete propellant charge deflagration in short barrels, you can get .300 BLK to experience full deflagration in a barrel 10 inches or even shorter.
This is the biggest thing to keep in mind if you’re eyeing .300 BLK for your next build, especially for an ARP. A .300 Blackout upper of 5 inches will outperform a similar upper with a barrel chambered in 5.56 because even if you compare apples to apples and make it about the speed and flat-shooting nature of the latter cartridge instead of about stopping power, the short barrel will rob some of the performance of 5.56. That won’t happen with .300 Blackout.
Installing a Muzzle Device Is a Good Move
Another great thing about .300 Blackout is that it performs well in suppressed builds. A muzzle brake is a good option, but a suppressor will offer some recoil reduction and a whole lot more than that.
Suppression makes the gun quieter, which makes a suppressor a really good option especially if you shoot subsonic rounds, which are fairly popular among .300 BLK. If you suppress a short build and shoot subsonic loads, you’ll be surprised how quiet the gun is.
This makes them highly practical as defensive platforms, especially since protecting your hearing in tight, indoor quarters is difficult with a firearm. A suppressed .300 BLK ARP shooting subsonic ammo is about as good as they come on that front, though.
Install a Bolt Carrier Group with an Advanced Coating
A mil-spec AR-15 bolt carrier group is good, but just that. It’s not great. There are many advanced bolt carrier groups with modern coatings that offer enhanced permanent dry lubricity that considerably boosts performance.
These bolt carrier groups, which sport coatings such as black nitride, titanium nitride, nickel boron and diamond-like carbon (or DLC) among others, are easier to keep clean because they don’t attract fouling, and can offer faster cyclic rates as well.
Plus, some of them, such as DLC and titanium nitride, which is also called gold nitride, offer really pleasant aesthetics as well, which is another reason to consider this upgrade. Anodized AR15 parts are not the only way to personalize the platform with unique colored components. You can do that with the bolt carrier group as well.
You May Need a Heavier Buffer If You Shoot Suppressed
Generally, a rifle chambered in .300 BLK will not need a heavier buffer, and in many cases, the .300 BLK performs just as well with a carbine buffer as a rifle chambered in 5.56. That calculus can shift when you suppress the platform, though, and since that’s one of the recommendations made here, it warrants another word.
Suppression does offer all of the benefits mentioned here, but it also considerably increases bore pressures, and that in turn puts a lot of pressure on the bolt carrier group that gets transferred to the buffer weight and spring when you fire the gun.
Therefore, in some cases, a suppressor .300 Blackout build will require a slightly heavier buffer. It might take some trial and error to determine what weight you need or even if you need a heavier one, though, so be ready to invest the necessary time.
Shop .300 BLK Uppers Here
Thinking a .300 Blackout upper in 5 inches is the right move for your next ARP build? Check out our collection of complete, assembled uppers in a variety of chamberings, and if you have any questions before you build, get in touch with us and we will be more than happy to assist.