Every few years we hear about a new caliber that is going to replace the 5.56 in the AR realm. They come and go like the wind. Very few stick around for long and when they do, they are only a small niche round. 300 blackout never met this fate, mostly because it never tried to replace 5.56, instead, it became an excellent companion to the 5.56 cartridge. The 300 Blackout was a slow burn but has reached a point where every company producing AR-15s is producing a 300 Blackout variant.

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With this in mind, you may be wondering which caliber should you choose for your next AR 15 build? That’s a good question and we can’t answer it for you. What we can do is present you the facts so you can determine which caliber is right for you.

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The 5.56 and 300 Blackout is very different rounds but they do have a lot in common. First and foremost these are both AR 15 rounds and work with standard upper and lower receivers. In fact, the 300 Blackout is compatible with almost every part and piece of a standard 5.56 AR 15.

These guns use the same receivers, BCGs, magazines, rail systems, stocks, buffers, and even the same gas block. The difference is the gas system length and barrel and that’s really it. This makes 300 Blackout an affordable build overall.

Both calibers are intermediate rounds and both are soft shooting and easy to control. They are also rounds you could use for a variety of tasks. This includes defensive, plinking, and even hunting medium game with. Both the 5.56 and 300 Blackout are excellent home defense calibers, and perfect for that role.

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As I mentioned previously, the reason the 300 Blackout is successful is because it complimented the 5.56. These two calibers are quite different and they aren’t trying to compete in the same race.

As I mentioned previously, the reason the 300 Blackout is successful is because it complimented the 5.56. These two calibers are quite different and they aren’t trying to compete in the same race.

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The 5.56 is a much better round for long-range use. With a proper rifle length barrel, the 5.56 round can be effective in terms of accuracy and energy out to 500 yards. The 5.56 round is much more common and it’s easier to find a multitude of different roles for different tasks. This includes rounds for hunting varmint, or rounds for hunting deer, or rounds design specifically for self-defense.

The 5.56 round offers less recoil than the 300 Blackout and is a much softer shooting caliber. 300 Blackout isn't a shoulder bruiser but you can feel the difference. With subsonic rounds, the recoil is less, but supersonics have more recoil than a 5.56 round.

5.56 guns are tougher to suppress, and the 5.56 round isn’t as potent in short barrels. However, if your goal is to have a standard rifle the 5.56 is the way to go. A 300 Blackout with a 16-inch barrel is a large waste of space and is better suited for shorter barreled SBRs and AR pistols.

Here is the thing, neither caliber is necessarily better than the other. They are better at certain tasks and in certain roles. You have to analyze what you want your AR 15 to do and choose from there. Do you want a suppressed short-barreled rifle or AR pistol? Go with the 300 Blackout. Do you want a rifle or a cheaper source of ammo? Go with the 5.56. Both calibers are successful for a reason and they work together well.