You can build another AR style rifle around 5.56 and play around with barrel length, buffer weight, or the style of handguard you use on the build and call it new.
Or you can experiment with a new chambering, like a .300 Blackout build, and actually reap some material benefits.
This cartridge, though similar to 5.56 (it is closely related, after all) offers some serious advantages in terms of ballistics over it. Here’s what you should know, and yes, the short answer is, if you don’t have a .300 BLK AR-style rifle yet, you should build one.
Better Ballistic Performance
The .300 BLK does not perform well past 100 or 200 yards because it, as some have observed, (and to quote) “drops like a rock in a sock.”
This is true, but it is also true that a .300 Blackout build will produce considerably more muzzle energy and therefore stopping power than 5.56.
This is highly dependent on load data, but you can expect a 5.56 round to produce anywhere from 1200 to 1360 ft-lbs of muzzle energy. By contrast, the .300 BLK is much more powerful, delivering anywhere from 1200 (or even lower) to 1400 or more ft-lbs.
The .300 BLK is also loaded with a larger, heavier bullet that will produce a wider wound channel. In other words, it delivers more power, and therefore is highly effective when loaded with a suitable bullet for defensive or sporting applications.
Better Performance from a Short Barrel
The 5.56 is a much faster, flatter shooting round, and performs best with a barrel 16” or longer, because that gives the propellant charge more time to deflagrate fully before the bullet leaves the bore.
Consequently, shorter barrels produce a lot of fouling and port pop, and it will cost you on FPS at the muzzle. ARPs in 5.56 may be common, but the shorter barrel is really only offering you compact maneuverability and not much more than that.
The .300 BLK round is designed to perform well from shorter barrels and will produce less fouling and port pop. As a result, SBRs and ARPs chambered in .300 BLK will perform admirably compared to those chambered in 5.56.
Better Performance Suppressed
In addition to the fact that a .300 Blackout build with a shorter barrel will perform better than a comparable one chambered in 5.56, it is also the case that this cartridge performs very well suppressed.
Pair these two things together, and you can build a smooth-shooting .300 Blackout build with a short barrel that doesn’t produce too much port pop or noise at all. On that same note, consider the fact that there are a lot of great subsonic loads.
There Are Great Subsonic Loads, Too
The great thing about .300 BLK subsonic loads is that the bullet is heavy and produces a lot of energy, so you shouldn’t have too much problem with reliability.
The other great thing about .300 BLK subsonic loads is that, when paired with a suppressor, you’ll barely even hear the rifle go off. This can offer several significant advantages in its own right.
But that’s not even the end of this; following on the heels of these advantages is the fact that, since this cartridge does not perform well past intermediate ranges, you don’t need to consider the dropoff in performance that subsonic loads usually incur.
Since you’ll likely be keeping effective shots with this round to 100 yards or closer, there’s hardly any tradeoff in performance between supersonic and subsonic loads. It’s a win-win in this scenario.
You Can Use Most of the Same Rifle Parts
Lastly, if you want to make a .300 Blackout build, it’s highly convenient that you’ll be able to use many of the same parts you’d be able to use with a 5.56 build.
You’ll need a new barrel and new magazines, but by and large, most of the parts designed for a 5.56 build will also work with a .300 BLK rifle, including the bolt carrier group.
Of course, if you have any questions about compatibility, get in touch with us at Sales@MCSGearup.com and we will be more than happy to clear up any questions that you have.
Shop .300 Blackout Builds Here
We carry a number of complete assembled uppers for .300 Blackout builds here ranging from micro AR pistols to full-sized rifles, as well as piecemeal upper and lower parts for builds, including bolt carrier groups.
Check out our collection to find the upper that works best for your build and if you still aren’t sure if .300 BLK is the right chambering for you, get in touch with us and we’ll be happy to assist.