5.56 vs 300 Blackout | What’s the difference?

Chevy or Ford? .45 ACP versus 9mm? comparing 300 Blackout (BLK) to 5.56mm NATO The arguments go on and on.

Even while I can make a case for the automobile brand wars, conflicts over calibers frequently continue because each side’s arguments usually contain some kernels of truth.

The issue of context is another. These arguments are frequently fought in broad terms of what’s “best,” without any clear guidelines for how “best” is chosen. Are Bugatti Veyrons superior to Jeep Wranglers? No, not if your goal is to navigate a pack mule track up a mountain.

Let’s examine the 5.56mm NATO vs. 300 BLK debate in more detail.

Why Is There a 300 Blackout?

The.300 AAC Blackout cartridge was designed with three straightforward objectives in mind: to have ballistics that are comparable to those of the 7.62x39mm (AK) platform, to deliver more “stopping power” when fired from a short-barreled rifle or pistol, and to outperform 9mm alternatives in the subsonic velocity range.

The first objective seems simple, right? Why not simply produce an AR-15 upper with a 7.62x39mm barrel and chamber?

To begin with, that would be emulating our adversaries, and that tactic is rather pathetic. What’s more, the sharply tapered rounds won’t load into regular AR magazines. There is still the issue of the AR’s vertical magazine well, even if you swap the magazines with something more banana-shaped to suit the slanted Commie Cartridges.

Describe it.

In reality, the 300 BLK is a shortened version of the.223 Remington. Instead of using a.224-inch diameter bullet, the brass case is cut, reshaped, and extended at the mouth to fit a.308 bullet. The overall cartridge length is still suitable with regular magazines even if the bullets are longer and heavier than their.223 Remington counterparts.

We’ll see in a moment how important the implications of it are. The case’s dimensions and body’s diameter are both the same. Although the shapes differ, the overall lengths are similar.

Platform Variations

It doesn’t take much surgery to convert a normal AR-15 rifle chambered in 5.56mm to 300 BLK because the cartridges are so similar. Actually, all you need to do is switch out the barrel. On an AR rifle or handgun, that is a straightforward operation. The barrel nut simply pulls out for an effortless swap after removal.

The bolt and bolt carrier have not changed since the cartridge base has not altered. The magazines can be switched out for one another for the same purpose. A STANAG (NATO Draft Standardization Agreement) magazine can be used with 300 BLK cartridges without any modifications. Oh, there’s yet another advantage. In contrast to “alternative” AR cartridge options like the 6.8 SPC, magazine capacity is also the same.


The bullet weight differential between 5.56 and 300 BLK is one to note. The weight of the “standard” 5.56 NATO bullet ranges from 55 to 77 grains. 110- or 125-gr. bullets are used in the majority of supersonic 300 BLK ammunition. Typically, the subsonic variant fires 220-gr. bullets.

Thus, a tradeoff results. While the heavier and thicker BLK bullets carry more energy downrange, the lighter 5.56 NATO bullets fire flatter over longer distances. More bullet drops are the price. The best option for you therefore depends on what matters to you the most.

To investigate how velocity and bullet drop carried with both the 5.56mm NATO and 300 BLK options, I ran the statistics with all four possibilities. The zero distance for both guns was set at 50 yards.

If you want to optimize the amount of energy on target, bullet weight is important. While the traditional unit of kinetic energy, the foot-pounds, represents destructive force, the companion unit of momentum, the pounds-feet per second, conveys an object’s capacity to propel another. Therefore, the BLK offering can be the correct choice for you if you’re searching for a heavier hit. The average muzzle velocity of 55- and 77-gr. 5.56 rounds is 22 to 28 pounds-feet per second. Projectiles weighing 125 and 230 g in 300 BLK range carry 36 and 33, respectively.

The cost of ammunition is another factor. The sheer volume of discharged rounds is advantageous for the 5.56 NATO globe. Companies invest more money to supply the market with countless billions of rounds the more people shoot it. As a result, you and I pay less per round. Both supersonic and subsonic 300 BLK cartridges typically cost more per round due to the reduced capacity of this caliber.

Did the.300 AAC Blackout accomplish what its creators had envisioned? In my opinion. The ballistics of the 300 BLK are comparable to those of the 7.6239, it performs well from a short barrel, and it outperforms the 9mm in subsonic and suppressed performance.

What is suitable for you? It’s similar to asking if you prefer two-wheel drive or four-wheel drive. For their respective applications, they both have benefits and drawbacks. The one that is best for you will depend on how you want to utilize it. Both the 5.56mm NATO and the 300 Blackout are effective defensive weapons.

5.56mm is more frequently utilized for small game and varmints in the world of AR-15 hunting, where fragmenting terminal performance is preferred. The BLK offers a more complete solution for larger games when penetration is more crucial.

The final verdict is this: lighter and faster versus heavier and slower. It sounds a lot like the argument between 9mm and.45 ACP, doesn’t it?

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