5.56 and .223 ammunition have been on the market for decades. Initially designed for the Armalite rifles and being placed into the hands of military personnel, the 5.56 NATO was extremely popular. To fill the void in the civilian market, the .223 Remington was born. While 5.56 NATO and .223 Remington are the same caliber, they are not the exact same cartridge, and not all rifles can fire both of them; but what’s the difference?
The 5.56 is loaded to a higher pressure than the .223. The 5.56 will have a flatter trajectory downrange even though the .223 will have a higher velocity. The .223 round holds less of its velocity over time so the 5.56 is a more efficient round.
By that tidbit of information, we might say that the 5.56 edges out in superiority compared to the .223. We need to dive into a little bit of history and ballistics to really understand our stance and see why we like the 5.56 a little more.
5.56 NATO & .223 Remington Ballistics Comparison
The ballistics between the .223 and the 5.56 do vary, and despite our stance of liking the 5.56 round better than the .223, the .223 does objectively outperform the 5.56 in muzzle velocity. Don’t worry; we’ll back up our choice in a bit. A velocity comparison chart can be found below:
| Distance | 5.56 | .223 |
| Muzzle | 3,130 ft/s | 3,250 ft/s |
| 100 yards | 2,740 ft/s | 2,849 ft/s |
| 500 yards | 1,484 ft/s | 1,557 ft/s |
Bullet energy also differs:
| Distance | 5.56 | .223 |
| Muzzle | 1,196 ft-lbs | 1,290 ft-lbs |
| 100 yards | 917 ft-lbs | 991 ft-lbs |
| 500 yards | 269 ft-lbs | 296 ft-lbs |
Now, while at first glance, this looks like 5.56 isn’t the best choice over the .223, think again. The 5.56 was designed to be fired under higher pressures and optimized for penetration and lethality while still being light enough to carry in mass amounts. While it may not translate directly in these charts, there’s a more tactical back story as to why the ballistics look how they do.
What Do You Use 5.56 and .223 for?
Initially, both rounds were intended for military use. The .223 round was developed along with a lot of other .222-style cartridges and needed to be designated from the competition and go through some manufacturer changes.
Before the military’s push to develop a fast, lightweight, and piercing round, the .222 cartridge was manufactured and advertised for varmint hunting. Those original manufacturers were personal fans of bench matches, too, so it was also a popular round for friendly marksman competitions.
The 5.56 round is actively used in the military with varying grain loads and designations different from civilian rounds, but we can still find 5.56 NATO on the shelves. AR-15 platforms are the most common rifle built for this particular round, and besides military use, the 5.56 is fun for tactical practice, shooting competitions, or friendly plinking.
It’s absolutely practical to hunt with 5.56 NATO and .223 Remington, but it’s not recommended for anything much bigger than whitetail. Coyote and other varmint hunting is extremely popular with both rounds.
Ultimately, anything within the 100-yard range that’s smaller than a whitetail is good game for this smaller cartridge. You may want to consider something with a little more stopping power for wild boar, those beasts will take a hit and keep on running.
.223 Remington History
The .223 came onto the scene in 1960 as an experimental round in the midst of a small-caliber/high-velocity race between ammunition manufacturers. Armalite essentially was trying to develop the AR-15, which was introduced around the same time.
The .222 Remington was originally designed for varmints and benched target competitions. It was a unique round that served as a launch pad for the .223; only the .224 had to be sorted out in between before finally settling on the .223 Remington.
The .222 design didn’t meet the requirements that the military wanted. Their parameters included maintaining an excess speed of sound at 500 yards. A few more intermittent rounds were developed and tested and remained sub-par. The .222 Remington special is actually the original name of the .223 Remington; this was changed in 1959 due to the number of competition rounds that were produced and tested.
Armalite actually helped in the design of the .223 and came up with a round that weighed 55 grains and was slightly longer than the .222. The .223 made its way into the military, was adapted to the 5.56x45mm NATO round, and then the .223 made its way into the civilian sporting firearm market.
5.56 History
The 5.56 (5.56x45mm or 5.56 NATO) is the more developed version of the .223. Developed in the 1970s, the 5.56 has the same measurements as the .223 but is loaded to a higher pressure in order to penetrate steel helmets and armor.
In 1970 NATO signed a document agreeing to replace the 7.62x51mm round. FN-Herstal officially created the 5.56x45mm from the .223. The 5.56x45mm was officially accepted by NATO in 1980 as standard in the military. It was officially the replacement for the 7.62x51mm cartridge.
The 5.56 NATO allowed military members to carry more ammunition without compromising velocity and penetrating power in combat situations. The M16 was well underway in production at this time and was the military platform to run this new bottlenecked cartridge.
Major Differences Between 5.56 NATO & .223 Remington
While there aren’t a lot of differences between the .223 and 5.56 rounds, the two big differences (pressure and case length) confirm that the 5.56 is the better of the two.
5.56 is rated at a pressure of about 58,000 psi, whereas the .223 sits at about 55,000 psi. This is significantly important when we look at chamber pressures. 3,000 psi might not seem like that big of a difference in cartridges, but it adds up to about a 10,000 psi difference in the chamber. Additionally the case is .125 inches longer.
That being said, firing a 5.56 NATO through a gun barrel made for the .223 is definitely not the smartest and is potentially an explosive mistake.
The 5.56 NATO also has a longer throat length by about .125 inches. This is also one of those measurements that would really not do well in a firearm built with clearances for the shorter .223 round.
Now, just because you can shoot .223 through a firearm barrel for 5.56 doesn’t mean you should. Performance could be lacking and not quite as stellar as using the right cartridge for the firearm, but it won’t blow up because of too much barrel pressure.
Why is 5.56 NATO Better Than .223 Remington?
Ultimately, the 5.56 is better in a practical sense, especially today when the market can fluctuate with ammunition availability. Not to get too doomsday-prepper on everyone, but it’s also a little smarter to buy a gun that can shoot two kinds of rounds relatively safely rather than the inverse.
Recently 5.56 has been readily available, and with the increasing popularity of AR platforms, usually, you’ll see someone using a .223 when hunting small to medium-sized game. While both rounds can be used for hunting, the .223 rifles are more likely to have compliant versions compared to the 5.56.
The 5.56 has also been shown to have a flatter trajectory than a .223 thanks to its bullet design and flight characteristics. When this is paired with its better penetration characteristics, the evidence stacks up in favor of the 5.56
The 5.56 is still in use and a standard round for military use today, and now it’s even more accessible to civilians for AR-15 platforms. The 5.56 has taken the .223 to some pretty cool places ballistically. The 5.56 has a standard 62-grain bullet, and with a steel penetrator, can damage tissues up to 20 inches deep under ideal circumstances and penetrate 3 mm of steel at 600 yards. The armor-piercing version of this cartridge can penetrate 12mm of steel at 100 yards.
Some 5.56 Criticism
Over the years and with extensive use of the 5.56, guns have changed. This round is no exception to receiving a little blowback regarding lethality and stopping power. What’s important to note is that a lot of this criticism can be traced back to an M16 versus M4 argument.
The 5.56 naturally performs better and has been optimized for the M16 20-inch barrel with a 1:12 twist and demonstrates a higher muzzle velocity than firearms with shorter barrels (physics is in charge of this). The M4 is a slightly different firearm (though mostly made of M16 parts) that uses the same round but instead has a 14.5-inch barrel with a 1:7 twist.
The M4 carbine’s build means the bullet leaves the barrel with a lower muzzle velocity and, therefore, has less of a potential for significant wounds and penetration depth into soft tissue or steel. The potential for less-lethal wounds when using an M4 is where the criticism of the 5.56 NATO being less than ideal for engaging enemies stems.
To match this criticism and have a better fit for the M4 carbine rifle that was (and still is) in regular military circulation, 5.56 bullet weights have been adjusted to varying degrees. The round still stands strong as a military cartridge.
Closing Thoughts
Respect is due to the .223 for making the way for the 5.56x45mm. It’s a close choice between the two and hard to take a stance on which is the best. Ultimately the 5.56 NATO and .223 Remington cartridges only have two key differences between them: pressure loading and case length. With the .223 being the parent of the militarized and optimized 5.56 they are similar, but the 5.56 has been improved.
The 5.56 is a lightweight, fast-flying, lethal round that takes the small calibers beyond just small game hunting or shooting groundhogs. These rounds are currently easy to find in stores and pack a little more damage despite a lesser velocity and bullet energy at fair distances.
The 5.56 NATO is optimized for weapons with a 20-inch barrel, and the firearms chambered for this round, and its pressures are significantly less likely to explode in a shooter’s face if .223 had to be used. Both can be sufficient for hunting a variety of medium to small game animals or used for defensive measures.
