There are advantages to .300 Blackout. There are advantages to 5 inch AR pistol uppers. And then there are advantages to 5 inch .300 Blackout uppers.
While most of you probably knee-jerk and build AR pistols with 5.56 uppers, there are some strong cases to build an ARP around .300 Blackout instead. Here are some of the best of them.
Concealment
This is, of course, tied to the length of the barrel and not to the chambering, so it is something it shares in common with 5.56. All the same, it represents a considerable advantage.
Our 5 inch AR pistol uppers are among the most compact out there. Some of the only shorter ones are 4.5 inch AR pistol uppers and they’re mostly chambered in 9mm.
These 5 inch AR uppers are excellent for this and can be concealed in tight spaces that larger rifles and even carbines would not even fit.
This makes 5 inch .300 Blackout uppers great for builds that will be used for defensive applications, truck guns, and more.
Lightweight Design
The shorter the barrel, the lighter the resulting ARP will be, and that naturally applies to AR pistols built with 5 inch .300 Blackout uppers.
They’re lighter and therefore easier to transport (and handle and shoot, recoil aside) than their larger counterparts.
And, on top of that, with an ARP in .300 BLK, you get the firepower of a full-sized rifle in what’s roughly equivalent in size to a handgun.
Easy Handling in Tight Quarters
Like any other AR pistol, regardless of size and weight, the one you build around .300 BLK is going to handle better in tight quarters than a full size rifle or even a carbine or SBR.
This makes an AR pistol an optimal choice as a defensive platform as it will offer considerably better performance in tight spaces for defensive engagements.
Better Stopping Power Than 5.56
Now let’s take a closer look at the real advantage of .300 BLK compared to 5.56, especially considering that these are similar cartridges and that many parts are interchangeable between them.
Despite the fact that you can even keep your 5.56 BCG with a .300 BLK build, the latter offers way better stopping power and not too much extra recoil than 5.56.
Take a look at two typical loads. We’ll look at one 5.56 round loaded with a 45 grain bullet that produces a muzzle velocity of 2866 FPS. For contrast we’ll compare it with a .300 BLK loaded with a 120 grain bullet that leaves the muzzle at 2207 FPS.
The .300 BLK round in question produces a lot more muzzle energy and it will carry it further downrange. For comparison, the .300 BLK indicated produces a muzzle energy of 1302 ft-lbs compared to just 789 for the 5.56.
Granted, the 5.56 round indicated is a light one, but even with a 62 grain bullet, a similar 5.56 round would produce only a little over 1000 ft-lbs of muzzle energy. The .300 BLK wins on every metric.
As a result, this is a far better cartridge than 5.56 for defensive applications, especially at close ranges, which is what you’d expect with an ARP. In fact, the few advantages that 5.56 has, such as a flatter trajectory, disappear when you’re building an ARP anyway.
Better Accuracy Than You Expected (and Better Performance from a Short Barrel)
First, a shorter barrel produces less whip. Second, one of the biggest advantages of .300 Blackout, in general, is that it performs very well from short barrels.
Hot, fast cartridges like 5.56 need a longer barrel in order to ensure that the entire propellant charge deflagrates. This doesn’t happen with ARP-length barrels, and so muzzle velocity is left on the table in addition to the fact that the guns themselves shoot dirty.
You won’t have this problem with .300 BLK, which only needs 10” or so of barrel to ensure the deflagration of the entire propellant charge, making it much more accurate and effective when fired from a short barrel.
By the way, for any of you reading this and considering investing in a short barrel rifle kit or build, this is another reason to choose .300 BLK for that project as opposed to 5.56.
Shop 5 Inch AR Pistol Uppers Here
As you can see, there are numerous benefits not just of building a micro ARP with a 5 inch AR pistol upper, but there are plenty of good ones to build specifically with a 5 inch .300 Blackout upper for all of the reasons that it outperforms 5.56 and other relatively similar rifle calibers.
Shop our collection of AR pistol parts and .300 Blackout uppers and if you have any questions about parts or compatibility get in touch with us at Sales@MCSGearup.com.