300 Blackout vs 556 – 2022 Comparison

| Last Updated: January 10, 2022

So you’re looking for a decisive answer about the 5.56 NATO vs .300 Blk debate? If you were to call the 5.56 NATO a hammer, the .300 Blk would be a sledgehammer with the same length handle. While one of these enjoys riches as one of the world’s most used military cartridges. The other is still lurking in the shadows. 

Let’s bring both of them under the limelight!

TL;DR: 300 Blackout vs 5.56

Take a peek at the quick comparison of these two cartridges. 

300 Blackout

300BLK

5.56 NATO

5.56 NATO

Pros

Item1

.30 cal bullet for more punch

Achieves max potential in a nine-inch barrel

Needs just a barrel change on a 5.56 AR-15

Designed for SBR’s. Works very well with suppressors

Heavy grain bullets (220 gr) can bring down the biggest game animals at short range

Item2

Less recoil and high muzzle velocity

Ubiquitously available at inexpensive rates

Flatter trajectory and can be used to reach 1,000 yards

Used by NATO forces. So there’s a lot of variety and data out there

Lightweight ammo means more carry capacity and lighter weapons

Cons

300 Blackout

Reduced recoil control

Suitable only for short range (<300 yds)

Slightly scarce and also thrice as expensive as a 5.56 NATO

5.56 NATO

Short barrel life due to high velocity and pressure

Compromises on stopping power at an increasing range

Prohibited in many states for hunting CXP2 or bigger game

Best For

300 Blackout

The .300 Blackout was designed for SBR’s and is suitable for CQB. It is good for hunting all types of game at short range.

5.56 NATO

Great for short or medium range use for plinking, varminting, and even defense. Amazing choice for SHTF.

300 Blackout Overview

The .300 Blackout was developed in 2010 as an answer to the ubiquitous requirement of a hard-hitting bigger bore bullet for the AR-15. This cartridge was developed around the .300 Whisper cartridge from Wildcat firearms. For one very obvious reason – compatibility with a suppressor.  

Additionally, the basic purpose was to develop a round that was compatible with M4 style mags and other components. Requiring minimal or replacement of standard-issue rifle parts for quick adoption. 

Photo credit: reddit.com

Also known as the 7.62x35mm, it was designed by Advanced Armament Corporation (that’s why it sometimes reads .300 Blackout AAC) in collaboration with Remington Arms. The round was approved by SAAMI in 2011. 

This cartridge uses a trimmed down 5.56 NATO case filled with fast burning powder and a .30 caliber bullet that ranges in weight from 78 to 220 grains. The .300 Blackout is available in both subsonic and supersonic loads and is ballistically very effective up to 300 yards. 

This cartridge can utilize its maximum potential in only nine inches of barrel length. This means that there is ample room to attach a suppressor that’ll eat another five to eight inches of overall barrel length. This makes this cartridge great from CQB and for the likes of special forces operations. 

5.56 Overview

The origins of the 5.56 cartridge date back to the year 1957 when Remington developed the venerable .223 Remington cartridge. For those who don’t know, the 5.56x45mm also officially known as the 5.56 NATO is almost the same as the .223 Remington. Except that it is loaded at a much higher operating pressure and has a .125” longer throat. A rifle chambered for the 5.56 can fire the .223, but vice versa is not safe. 

Anyways, the 5.56 NATO was developed in the 1970s by FN Herstal. It is one of the most widely used cartridges by the militaries of NATO and non-NATO countries. The 5.56 NATO was adopted in 1980 as a replacement for the 7.62x51mm cartridge which had more recoil and weight. 

Photo credit: tacticalhq.co.za

The 5.56 NATO cartridge fires a .22 caliber bullet ranging from 40 to 77 grains in weight. It is a supersonic cartridge where the bullet can maintain its supersonic speed beyond 500 yards. The most appropriate and common twist rate for these bullets is 1:7. 

The effective range of a 5.56 NATO round is about 600 yards. However, match-grade ammo under ideal conditions can be used to hit paper targets at about 1,000 yards. 

These bullets are great in terms of recoil and mid-range accuracy. But their stopping power has sometimes been questionable. Like with the khat-eating terrorists of Somalia or during close quarter battles in Iraq or Afghanistan. 

300 Blackout vs 5.56: Cartridge Specs

Let’s compare these two cartridges side by side for dimensions and basic ballistical data. 

300 Blackout5.56
Bullet Diameter0.308 in (7.8 mm)0.224 in (5.70 mm)
Neck Diameter0.334 in (8.5 mm)0.253 in (6.43 mm)
Base Diameter0.376 in (9.6 mm)0.377 in (9.58 mm)
Case Length1.368 in (34.7 mm)1.760 in (44.70 mm)
Overall Length2.26 in (57 mm)2.260 in (57.4 mm)
Case Capacity25.4 gr28.5 gr
Max Pressure (SAAMI)55,000 psi62,366 psi
Typical Casing MaterialBrassBrass
Typical Bullet Weight (gr)78-190 gr40-77 gr

The 5.56 NATO and .300 Blk are both rimless bottlenecked cartridges with the same parent case. The .300 Blk is just a nick shorter in overall length and almost 0.4 inches shorter in case length. Hence it holds less powder than the 5.56 NATO. 

The extra case capacity and the pressures for which the 5.56 NATO is loaded, combined with the light bullet mass is what keeps those bullets supersonic at distant ranges. Along with a longer effective range when compared with the .30 cal bullet of the .300 Blk. 

Both these cartridges can be fed from the standard STANAG magazines interchangeably. Since the .300 Blk was intentionally designed for that. When you compare these cartridges side by side, you’ll notice that even with their similar length, the bottleneck position of the 5.56 NATO is ahead of the ogive of the .300 blk. This may cause feeding issues if you forcibly cram rounds into the mag. 

To overcome this, I’d suggest you use mags specially designed for the .300 Blk. Additionally, if you are using mags interchangeably, make sure you mark them so you don’t accidentally feed a .300 Blk in a 5.56 AR. 

Photo credit: lynxdefense.com

300 Blackout vs 556: Ballistics

Now let’s come to the actual comparison. First, we will be looking at the ballistics of these two rounds. But before we begin comparing the stats. There’s one point that has to be kept in mind. 

The .300 Blackout was designed for a short barrel. It works best with a short nine-inch barrel. Whereas the 5.56 NATO is an exclusively supersonic round that works best with 16 and 20-inch barrels. So you should not expect the 5.56 NATO to outperform the .300 Blk in shorter barrels and at close range. The ballistics data of the .300 Blk is somewhat similar to 7.62x39mm

We’ll be covering the trajectory, velocity, and energy of these rounds here. 

300 Blackout vs 5.56: Trajectory

A trajectory is an essential part of determining if a cartridge is suitable for medium to long range shooting. Heavier bullets tend to drop quicker as the distance increases. Unless they have been designed to overcome drop and wind disturbances. 

As far as intermediate cartridges are concerned, the 5.56 NATO and .300 Blk have a couple of amazing competitors like the 6.5 Creedmoor. But let’s only stick to their data at this moment. 

.300 Blackout

9” barrel/BC .320/125 gr Supersonic16” barrel/BC 0.437/ 190 gr Subsonic16” barrel/BC 0.290/110 gr Subsonic
100 yds: 0” Drop100 yds: 0” Drop100 yds: 0” Drop
200 yds: 8” Drop200 yds: 33.4” Drop200 yds: 6.45” Drop
300 yds: 29” Drop300 yds: 104.6” Drop300 yds: 23.19” Drop
500 yds: 130” Drop500 yds: 374.2” Drop500 yds: 101.37” Drop

5.56 NATO

9” barrel/BC .304/62 gr M855A1 Supersonic9” barrel/BC .300/112 gr Subsonic20” barrel/BC 0.220/55 gr Supersonic
100 yds: 0” Drop100 yds: 0” Drop100 yds: 1.4” Elevation
200 yds: 4.2” Drop200 yds: 34.1“ Drop200 yds: 0” Drop
300 yds: 17.2” Drop300 yds: 109.2” Drop300 yds: 7.2” Drop
500 yds: 40.9” Drop500 yds: 400.1” Drop500 yds: 47.7” Drop

Before we make a neutral comparison between the trajectories of a 5.56 NATO and a .300 Blk. It is important to note that these cartridges were designed for different barrel lengths. While the 5.56 NATO requires at least a 16-inch barrel to utilize its maximum potential. The .300 Blk needs only a nine-inch barrel. 

Let’s look at the lowest bullet weights first. Since the .300 Blk uses a heavier bullet, it will obviously have a higher drop. Even with supersonic ammunition. As you can see in the table above, the .300 Blk is a 300 yard round at most with its fastest bullets. 

Photo credit: thearmorylife.com

Moving on towards the heavy bullets. The .300 Blk ammo shows significant drops even at 200 yards. The 5.56 NATO on the other hand has a flatter trajectory in comparison. The 112-grain projectile mentioned in the table above is rarely used and is just to show you what a heavy 5.56 NATO bullet is capable of. 

62 grain is the most commonly used bullet weight for the 5.56 NATO. It is also what the Military uses. 

300 Blackout vs 5.56: Velocity & Kinetic Energy

This table here analyzes the velocity and kinetic energy of the .300 Blk and 5.56 NATO bullets at different ranges. The calculation points include 100, 200, 300, and 500-yard ranges. I did not include the 400 yards range because mostly it will be a mid-range shot within 300 yards or a long range shot at or beyond 500 yards.  

.300 Blackout

9” barrel/BC .320/125 gr Supersonic16” barrel/BC 0.437/ 190 gr Supersonic16” barrel/BC 0.290/110 gr Supersonic
100 yds:  1,771 ft/s, 870 ft.lbs100 yds:  1,599 ft/s, 1,078 ft.lbs100 yds:  2,099 ft/s, 1,077 ft.lbs
200 yds: 1,562 ft/s, 677 ft.lbs200 yds: 1,476 ft/s, 919 ft.lbs200 yds: 1,844 ft/s, 830 ft.lbs
300 yds :1,378 ft/s, 527 ft.lbs300 yds: 1,360 ft/s, 780 ft.lbs300 yds  1,611 ft/s, 634 ft.lbs
500 yds: 1,111 ft/s, 342 ft.lbs500 yds: 1,153 ft/s, 561 ft.lbs500 yds: 1,233 ft/s, 371 ft.lbs

5.56 NATO

9” barrel/BC .304/62 gr M855A19” barrel/BC .300/112 gr Subsonic20” barrel/BC 0.220/55 gr Supersonic
100 yds: 2,308 ft/s, 733 ft.lbs100 yds: 979 ft/s, 238 ft.lbs100 yds: 2,837 ft/s, 983 ft.lbs
200 yds: 2,045 ft/s, 576 ft.lbs200 yds: 922 ft/s, 211 ft.lbs200 yds: 2,468 ft/s, 744 ft.lbs
300 yds: 1,802 ft/s, 447 ft.lbs300 yds: 891 ft/s, 191 ft.lbs300 yds: 2,128 ft/s, 553 ft.lbs
500 yds: 1,384 ft/s, 264 ft.lbs500 yds: 798 ft/s, 158 ft.lbs500 yds: 1,540 ft/s, 290 ft.lbs

What is clearly evident from this data is that a 5.56 NATO is obviously a faster round than the .300 Blk. However, the latter has more punching power at short or even long distances. The heavier bullet weight definitely helps with that. 

It is also important to note that the lighter bullets in a .300 Blk (especially supersonic) are capable of higher velocities and impact. It eventually depends upon the bullet weights and you may find a good compromise at some point in between. 

The length of the barrel does impact velocity. However, the .300 Blk shows almost the same effective range when fired from a 16-inch barrel and a nine-inch barrel (at around 2,050 fps). 

The .300 Blk is best to be used in supersonic loads. Subsonic ammo may be good at penetration but lacks fragmentation. Hence not creating a significant wound channel. 

300 Blackout vs 556: Stopping Power

Coming to the real question. Let’s evaluate the stopping power of each of these cartridges. The whole point of development of the .300 Blk was to get more stopping power than the 5.56 NATO that too in a shorter barrel. 

The stopping power of a round measures its ability to either incapacitate or immobilize a target. Plus, we’ll also cover the concept of barrier blindness. 

300 Blackout vs 556: Momentum & Sectional Density

Maybe things are getting a bit too technical here. But to understand the actual stopping power of these rounds. It is important to study the momentum and sectional density. I’ll explain it further in detail. Just take a look at the numbers first. 

.300 Blk Momentum 

9” barrel/BC .320/125 gr Supersonic
Sectional Density: 0.188
16” barrel/BC 0.437/ 190 gr Supersonic
Sectional Density: 0.286
9” barrel/BC 0.290/110 gr subsonic
Sectional Density: 0.166
100 yds: 31.625 lb ft-s100 yds: 43.401 lb ft-s100 yds: 32.984 lb ft-s
200 yds: 27.892 lb ft-s200 yds: 40.062 lb ft-s200 yds: 28.977 lb ft-s
300 yds: 24.607 lb ft-s300 yds: 36.914 lb ft-s300 yds: 25.315 lb ft-s
500 yds: 19.839 lb ft-s500 yds: 31.295 lb ft-s500 yds: 19.375 lb ft-s

5.56 NATO Momentum

9” barrel/BC .304/62 gr M855A1
Sectional Density: 0.177
9” barrel/BC .300/112 gr Subsonic
Sectional Density: 0.319
20” barrel/BC 0.220/55 gr Supersonic
Sectional Density: 0.157
100 yds: 20.442 lb ft-s100 yds: 15.664 lb ft-s100 yds: 22.290 lb ft-s
200 yds: 18.112 lb ft-s200 yds: 14.752 lb ft-s200 yds: 19.391 lb ft-s
300 yds: 15.960 lb ft-s300 yds: 14.256 lb ft-s300 yds: 16.720 lb ft-s
500 yds: 12.258 lb ft-s500 yds: 12.768 lb ft-s500 yds: 12.100 lb ft-s

So before we analyze these numbers. Let’s understand the concept of sectional density and momentum. 

In simple terms, sectional density is the ratio between a bullet’s mass and the square of its diameter. In even more simplistic terms, sectional density is a number that expresses the penetration capability of a particular bullet. Taking into account its weight and diameter (cross-section). 

Winchester developed a classification system that divides game animals of different sizes. It is known as the CXP (Controlled eXpansion Performance). Game animals are classified under CXP 1, 2, 3, or 4 classes. 

The CXP 1 class of game animals includes small varmints, typically weighing less than 50 pounds. The CXP 2 class includes heavier animals like deer, antelope, goats, and black bears. CXP 3 covers animals from 300 to 1,000 pounds and CXP 4 covers the biggest and toughest animals like cape buffalo, hippo, etc. 

A sectional density of 0.180 is good for small animals (CXP1). .200-.230 is good for medium game (CXP 2), .270-.280 for larger animals (CXP 3), and .300+ for anything bigger (CXP 4). 

Bullet momentum is the measure of the quantity of motion an object has. In simple terms, momentum is also an important factor that decides how much a bullet will penetrate. Or the ability of the bullet to transfer its kinetic energy. 

Photo credit: americanfirearms.org

300 Blackout vs 5.56: Use Cases & Effective Range

Now let’s bring this discussion to a more practical table. Understanding the effectiveness of each of these calibers in a few use cases and circumstances will help you better understand their potential. 

Small or Medium Game Hunting

Both the .300 Blk and 5.56 are great medium game hunting cartridges. The .300 Blk may feel like overkill for a small game (which it is). The 5.56 NATO is perfect for small game and varminting. However, 5.56 NATO may not be a great deer killer and it is certainly banned in several states to hunt deer with it (with light grain bullets). Not to mention other bigger game. 

Big Game Hunting

Choosing the 5.56 NATO for big game hunting is clearly out of the question. The 5.56 NATO 62 gr bullet drops under 1,000 ft-lbs at 100 yards. Which is certainly not good for big game. Additionally, the small fast-moving bullet is also not expected to create a large wound channel. 

The .300 Blk on the other hand can have a sectional density of more than .300 in its heaviest bullets. Making it good for hunting almost anything at the appropriate range. 

Range Practice

The deciding factor when choosing either of these cartridges for range practice is the effective range and price. .300 Blk can cost almost twice as much compared to 5.56 NATO. If you just want to punch paper targets or steel at the range. The 5.56 NATO is a better choice. 

On the contrary, if you want to fire .30 cal semi-auto on a budget. Probably get an AK-47. 

Long Range Shooting 

Considering the trajectory character of these bullets. The .300 Blk is not even close to being a reputable long range cartridge. It also doesn’t have to be because it was designed for CQB with short barrel rifles. 

The 5.56 NATO is a clear winner for long range use with an effective range of 800-1,000 yards. Although the drop will differ with a different bullet weight and barrel lengths. It is still manageable. Plus, the high velocity and low mass of 5.56 bullets give them an edge. 

Photo credit: youtube.com

Home Defense

That’s a somewhat tough question to answer. I don’t think rifles are great for home defense. Especially in an urban setting. The .300 Blk has a short range and better stopping power, but it has a higher level of barrier blindness. This means it can easily penetrate drywall or doors. 

The 5.56 NATO is a smaller bullet with lesser penetration, but it does not guarantee zero penetration. Overall, the .300 Blk was designed for SBR’s with suppressors. At common self-defense encounter range (within 20 feet), none of the ballistics characteristics matter. The obliged receiver of the bullet won’t notice the difference. But you still have to consider penetration. 

300 Blackout vs 5.56: Costs, Availability, & Compatibility

Coming to the economics, logistics, and versatility of these cartridges. Let’s try and understand their effect on your wallet and if you can trust the market’s supply chain when SHTF. 

Cheap ‘n Abundant vs Pricey ‘n Sparse

5.56 NATO is like the 7.62 AK ammo. Due to their wide usage, there’s always a constant and cheap supply of ammo. From manufacturers to milsurp discount crates. 5.56 NATO ammo is cheap and can be found on every gunshop’s shelves. 

On the other hand, the .300 Blk doesn’t circulate that much. The biggest deterrent is the price which can be almost three times as high for match-grade ammo. Plus, there are cheaper .30 cal alternatives. Also, don’t forget the AR-10

While the 5.56 NATO is easily available compared to the .300 Blk. We saw an unprecedented shortage of ammo on the market during the peak of the Covid-19 pandemic in 2020. The 5.56 was scarce and costly but you could get your hands on something (fresh ammo or reloading supplies. But the .300 blk almost went extinct for a few days. 

Lesson to be learned? Always keep backup ammo. Especially for uncommon cartridges. 

Photo credit: youtube.com

Enjoy Both with the Swap of a Barrel

The best part of using these two cartridges is their interoperability. The .300 Blk was designed to run on a 5.56 NATO chambered AR-15. The only thing that needs to be changed is the barrel. So basically, you can run two ballistically different cartridges in the same rifle without much change. 

Bottom Line

The .300 Blk was designed to impart the power of a .30 caliber bullet to a 5.56 M4/AR-15/. Both these cartridges use the same parent case which makes them interchangeable without even changing the BCG. Which was what the designers wanted originally. 

The .300 Blk is a hard-hitting cartridge with heavier bullets than the 5.56 NATO. It was designed for use in SBR’s with/without suppressors. In short, for close range combat in the modern battlefield. However, this extra stopping power comes at the cost of a shorter effective range. 

The 5.56 NATO has been the standard issue cartridge of many armies across this world. It is lightweight so you can carry more and also recoils very little. The .224 inches bullet is great for incapacitating human combatants and great for varminting. It is also readily available and far cheaper than the .300 Blk. 



Ankit Kumar is an engineer turned writer who specializes in topics related to firearms, gun safety and weapon tech. His passion towards enrolling in the Army drifted his interest towards light and heavy firearms. He’s a qualified competitive air rifle shooter and an avid nature lover. His other areas of expertise include survival, prepping and firearms/ammo storage. When he’s not writing, he’s either learning a new skill, trekking or enjoying a long drive.