5.56 vs. 300 Blackout:  Which Caliber is better?

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We see a lot of questions about the .300 Blackout vs 5.56 Nato calibers, so we wanted to take this time to set the record straight.

If you’re wondering which to go with, or which one might be more useful for you, we’re going to go over everything you need to know to choose.

Let’s talk about these two super popular AR-15 calibers. We’ll go over all the important details that separate the two and make them each special in their own way.

About .300 Blackout

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The .300 Blackout was developed by Advanced Armament Corporation in conjunction with Remington’s defense arm. The idea was that it would be used with military M4s and civilian AR-15s. 

The original goal was to have a .30-caliber projectile that was ballistically similar to the Russian 7.62x39mm round in an M4/AR-15 platform. It is based almost completely on the wildcat .300 Whisper cartridge, but was standardized and then submitted to SAAMI for certification.

Years later, the .300 Blackout has become one of, if not the most popular alternative cartridges for the AR-15 platform. It sees use by military and law enforcement agencies, as well as by civilian hunters and sport shooters. 

The first publicly known military use of the cartridge came about in 2015 when the Netherlands issued 195 Sig MCXs chambered in .300 Blackout to their special operations forces.

Since then, many other SF groups have fielded the .300 Blackout in one form or another, mostly because of its close-range terminal ballistics and excellent performance in short-barreled and suppressed rifles and carbines.

In civilian circles, the round is beloved by short-barreled rifle owners and those who want the utmost suppressed performance. It’s also a big hit among those who want to hunt with a mostly standard AR-15 as the 5.56x45mm has limited effectiveness against medium-sized game animals. 

About 5.56x45mm NATO

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5.56x45mm NATO came about in the early 1960s as a refinement of the .223 Remington for military use. The goal was to create a smaller and lighter intermediate cartridge as an alternative to the 7.62x51mm NATO for standard infantry rifles.

The original design was produced alongside the development of the AR-15, and what would go on to become the M16. The original design brief for the rifle that would come out of this development had the following criteria:

  • .22 caliber
  • Bullet exceeding supersonic speed at 500 yards
  • Rifle weight of 6 lbs
  • Magazine capacity of 20 rounds
  • Select fire for both semi-automatic and fully automatic use
  • Penetration of US steel helmet through one side at 500 yards
  • Penetration of .135-inch steel plate at 500 yards
  • Accuracy and ballistics equal to M2 ball ammunition (.30-06 Springfield) out to 500 yards
  • Wounding ability equal to the M1 carbine

After several years of development and testing, the first 5.56 NATO rifles and ammo were issued towards the beginning of the Vietnam War in 1970.

In the years since 5.56x45mm has become the round of choice for NATO and allied forces around the world. Billions of rounds have been produced, and millions are fired every year by civilians, as well as law enforcement and military personnel. 

.300 Blackout vs 5.56mm NATO: Head to Head

Now, we can’t declare either one of these rounds the best because they’re for different things. What we can do, however, is help you, dear reader, decide which one is best for you.

Best Suited For5.56 Nato.300 BLK
Hunting 
Target Shooting 
Home Defense
Varmint Shooting 
Suppressed Use 
Mid Range (300-600m) Shooting 

The short version is, the 5.56 is more accurate and better at extended range, while the .300 BLK has more of an impact on organic targets at close range, and works better with a suppressor. 

The big thing to keep in mind is that there’s no one round to rule them all here. Both of these rounds have their own strengths and weaknesses and are better at different things.

The good news is, if you can’t decide, you can simply get two different uppers and be ready to go. The two rounds use the same mags, and you can just swap uppers back and forth in about 15 seconds, maybe 10 if you hurry.

Popular Article: 17 Best Long Range Calibers

On the other hand, if you’re just building your first rifle, or only want to spend the money on one and want to know which one to pick…I can’t tell you what to do.

But I can tell you what you need to know so that you can choose for yourself.

5.56 Nato: Biggest Strengths and Weaknesses

First up, let’s talk about what the 5.56 NATO is good at, and what it’s not so good at. 

This round excels at being lightweight and low-recoil, but still having enough power to stop a two-legged threat. That’s what it was designed for, after all. It’s very flat shooting, has a high velocity, next to no recoil, and the ammo weighs almost nothing.

This high velocity and lightweight makes it an excellent choice for a tactical rifle as you can carry hundreds of rounds without loading yourself down too much (standard combat load for most infantry is 210 rounds). 

It is also very effective at creating a large temporary wound cavity, which effectively leaves a much larger hole than the size of the actual projectile. This effect is called hydrostatic shock and is one of the reasons that high-velocity rifle rounds are so deadly.

Where it starts to fall down is in the terminal ballistics department, and in those times when you actually want less velocity, which we’ll talk more about in a minute.

First, we have to look at some of 5.56’s ballistic issues. Namely, the .22-caliber projectile doesn’t fight wind super well, and it has less of an impact on a soft target than the .300 BLK does.

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The 5.56’s velocity also works against it in some ways, in that subsonic 5.56, when you can find it, tends to suck. Really, really badly. You can have a big slow bullet do well, or you can have a small fast bullet, or a big fast bullet, all of which will have their pros and cons.

A small slow bullet though? Forget about it.

For this reason, suppressing the 5.56, while perfectly viable, isn’t as successful as suppressing other, slower rounds like the .300 Blackout. You’re always going to hear that supersonic crack with a 5.56.

The 5.56 also requires about an 11.5” barrel to get the most velocity and downrange power possible, which makes for some fairly long guns most of the time. 

.300 BLK: Biggest Strengths and Weaknesses

.300 BLK excels when used in a suppressed SBR, and it offers superior close-range terminal ballistics by the simple expedient of utilizing bullets that are 2-3x heavier than the heaviest 5.56mm bullets.

This makes the .300 BLK much better for hunting medium-sized game, especially in close quarters. This round is truly beloved in the South where feral hogs are beginning to overrun farms in some places. At this point, .300 Blackout can truly be said to be bringing home the bacon.

Literally.

Beyond that, .300 BLK works great with a suppressor as you can easily shoot supersonic and subsonic munitions from the same rifle without any modifications or adjustments.

It also burns its powder in about a 9” barrel, so it works great with AR-15 pistols and short-barreled rifles alike with no loss of performance.

5.56 vs .300 BLK Ballistics

Ballistically, .300 BLK and 5.56 are fairly different.

Round + Barrel LengthBullet WeightVelocity at MuzzleEnergy + Drop @100 YardsEnergy + Drop @200 YardsEnergy + Drop @300 Yards
5.56 16” barrel55gr2800fps742ft. lbs +0”567 ft. lbs/
-4”
426 ft. lbs/-16”
5.56 20” barrel55gr3100fps919ft. lbs + 0”711 ft. lbs/
-3”
542 ft. lbs/ -12”
.300 BLK 16” Barrel125gr2240fps1312ft. lbs + 0”1068 ft. lbs/ -5.9”882ft lbs/-21”
.300 BLK 9” barrel125gr2100fps993ft. lbs + 0”799ft. lbs/-8”641 ft. lbs/-29”

Immediately, we can see that the .300 BLK has a much lower velocity, but a much larger projectile size that translates into better energy retention downrange.

The downside of this is the .300 BLK drops by almost twice as much out to 300 yards, and it only gets worse after that. There are certainly better long-range calibers out there, so follow that link and read that article if you’re looking at hitting things past 400 yards.

In a standard 16” civilian barrel, the .300 BLK has about double the energy at 100 yards than the 5.56 does, which translates into a more lethal effect on a living target. 

This is why the .300 BLK is so popular with hunters, especially hog and deer hunters in areas that don’t typically see three and four hundred yard shots.

We can also see the rather precipitous drop from the .300 BLK that makes the 5.56 much better at 300 yards plus. If you need to be accurate past 300 yards, or really past 200 yards, 5.56 is simply easier to get hits with.

General Purpose Shooting

At the range for close-in target shooting (less than 100 yards), the ballistics of the two rounds are close enough that there’s not a huge difference between the two. For punching paper or ringing steel, either one will do just as well as the other.

That said, because the .300 BLK has about 3x the recoil energy of the 5.56, you will have a little more work to do when it comes to rapid strings of fire and reacquiring your target quickly.

The other thing to consider is the cost and availability of ammo. The .300 BLK is considerably more expensive to buy off the shelf than 5.56 is, and there’s a lot less variety to choose from.

I’ll typically see a dozen or more different flavors of 5.56 available when I go to the store, versus maybe 4 or 5 .300 Blackout options. If you’re good with ordering ammo online and you aren’t super worried about the overall price to feed your rifle, .300 Blackout is okay here.

Related Article: 20 Best BB Guns – BB Rifles & BB Pistols

So where does that leave us for general purpose shooting and target work? Because of the better-ranged performance, cheaper ammo, and higher mag capacity, we have to give this one to the 5.56.

Self/Home Defense Shooting

This one can really go either way. On the one hand, lighter ammo, less recoil, and higher velocities are all great for tactical shooting in a defensive situation. 

On the other hand, bigger holes in the target and less risk of blowing your eardrums out are also good. There’s a reason police and urban counter-terror groups are starting to look into the .300 Blackout. 

At the end, where the defensive shooting crown winds up comes down to whether you’re running a full-length rifle or not, and whether you’re running a suppressor or not. 


If you’re suppressed or using an SBR or AR-15 pistol, definitely go with .300 BLK. If not, 5.56 is fine and you won’t get a huge amount of benefit from the .300 BLK.

Hunting

If you’re hunting larger game like whitetail deer or wild hogs, then the larger bullet of the .300 BLK is definitely the way to go (especially if you’re going all out and hunting with a suppressor).

That said, if you’re sniping coyotes or prairie dogs from a quarter-mile away across the open plains, then the 5.56 is definitely the better bet.

At close ranges, particularly in the American South where you’re often hunting in thick cover, .300 Blackout is much preferred most of the time. Out West, 5.56 is probably going to do you a bit better.

Best .300 Blackout Suppressor

Our favorite .300 Blackout Suppressor is the Gemtech GMT-300. This 6.7” suppressor is designed specifically for the .300 Blackout, and the performance with subsonic munitions is shockingly good.

It utilizes a proprietary baffle design to eliminate as much sound as possible, and the two-piece sleeved design allows you to easily disassemble it for cleaning.

It is a bit heavy at 14oz, but on a short 9” barrel you don’t really notice the extra weight. On a full 16” barrel it might get a little cumbersome, but 9” barrels aren’t hard to get ahold of, and neither are pistol braces if you don’t want to go through the hassle of getting an SBR stamp.

Best 5.56 NATO Suppressor

Next up, let’s look at our favorite 5.56x45mm suppressor, the SureFire SOCOM556-RC2. 

Don’t let the crazy long name throw you off, this suppressor was designed by serious shooters for serious work. It’s 6.2” long, weighs in at just over 1lb, and is rated for full-auto fire.

The baffling (the internal parts that break up the sound wave and keep your gun quiet) are custom-designed to work with the 5.56 round and its ultra-high velocity, making for a nearly hearing-safe shooting experience. 

Best .300 Blackout Upper

We’ve listed the Aero Precision M4E1 Complete rifle before in our list of best .300 Blackout rifles, so it probably isn’t much of a surprise that it wound up on the list here too. 

The M4E1 upper is a high-quality product that offers many great features like a stellar handguard, sling attachment points, and beautiful machining and finishing.

Aero has really maximized the benefit for customers wanting a new upper to go on an existing lower, but the fact that you can get a matched lower that you know will function reliably with your upper, and is maybe even painted to match, is just icing on the cake.

Best 5.56 NATO Upper

Just get the M4E1, but this time in 5.56.

Seriously, in terms of value and performance, it’s hard to beat the Aero Precision offering, especially if you’re looking for a more DIY approach, or you want something colorful like a blue or red Cerakote, or one of their special themed designs (stormtrooper AR-15, anyone?).

Both versions feature an awesome chrome moly vanadium barrel, an enhanced M-LOK or KeyMod handguard, a low-profile gas block, and an unpinned muzzle brake/flash hider on the barrel.

It doesn’t include a charging handle or bolt-carrier group, which is fine, just remember that you’ll need to pick those parts up too.

Final Verdict

.300 Blackout and 5.56 NATO are both great rounds that have their place in the world of military and civilian use. There’s no way to call one intrinsically better than the other because it’s an apples and oranges comparison.

All we can do is tell you what each one is best for, and how they perform so that you can decide which one best suits your needs.

Or, you could always just get two uppers and shoot both. That works too and gives you the best of both worlds. And since you can have uppers mailed straight to your doorstep, you don’t even have to leave the house to get them.

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