Even though most ARs and ARPs are chambered in .223 or 5.56, that doesn’t mean you should limit yourself to these cartridges. There are many better options out there, especially for AR pistols. 

One of the best examples of this is the .300 Blackout, also known as .300 BLK. Here are some of the top reasons you should make your next ARP a .300 Blackout build.

Better Stopping Power

If you’re building an ARP, chances are you have a reason for doing so that is not sporting. No one hunts with an ARP and few people just take them to the range plinking. That means your intended application is likely defensive. 

That being said, the .300 Blackout considerably outperforms the 5.56 and .223 when it comes to stopping power, particularly up close. Muzzle energy and stopping power depend on load data but in general there is a gulf of several hundred foot-pounds of energy between them. 

This makes the .300 BLK far superior for defensive applications, especially at close ranges, than 5.56 or .223. 

There are things that .223 does better; for instance, it shoots flatter (the .300 BLK is abysmal at long ranges) but let’s be serious, that advantage is hardly even relative here. No one is going long-range shooting with an ARP. 

On top of that, since the .300 BLK and 5.56 are similar cartridges, you can use a lot of the same AR parts with a 5.56 build as you can with a .300 BLK build. Even the bolt carrier group is the same. The main differences are the barrel and magazine. 

Which means that, if you are building for defensive applications, the a .300 Blackout build is better.

Better Performance from a Shorter Barrel

Another massive advantage of a .300 Blackout build, especially if we’re talking about building an ARP, is that .300 BLK performs much better from a shorter barrel whereas 5.56 does not. 

The 5.56 is a fast, flat-shooting cartridge but it needs a longer barrel, generally 16 inches or longer, before it can generate the desired muzzle velocities to get the desired performance from the round. 

Conversely, .300 BLK performs very admirably from barrels as short as 10 inches, and in some cases even shorter. In fact, you’ll get full propellant deflagration and the desired performance from the cartridge. 

With a shorter barrel, you’ll not only forfeit some muzzle velocity and energy with a 5.56 round, but you’ll also get less complete powder deflagration, which will make your ARP run a lot dirtier, result in an accelerated accumulation of fouling, and necessitate more frequent cleaning.

Where to Get a .300 Blackout Build 

These are the two most significant reasons that a .300 Blackout build is better for an ARP than 5.56 is, but there are others. Either way, if you’re convinced, check out MCS Gearup to find what you need. They carry a wide variety of AR parts, including assembled uppers and AR pistol uppers. Check out their website and get in touch with them for more assistance if you need help.

For more information about Glock Kits and Buffer Tube Accessories Please visit: MCS Gearup.