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5.56 vs .223: Definitive Guide To Which Is Superior [in 2024]

Antonio Salituro | Updated February 22, 2024 | Why You Should Trust Us | How We Earn Money
5.56-vs-.223 cover photo

Spend a few days on the shooting range, and the 5.56mm NATO vs .223 Remington debate will likely come up.

But knowing the difference between the two could mean choosing a round that greatly lowers your accuracy or, worse…

Causing a dangerous pressure spike, damaging your rifle, and causing a misfire.

Key Takeaways

  • The 5.56mm NATO and the .223 Remington ammunition have similar shapes and diameters, but they also have differing characteristics that largely affect the performance of a weapon.
  • While you can fire a .223 Rem. in a rifle chambered for a 5.56 NATO cartridge, you can’t do the vice versa as it’s unsafe and can damage the weapon or the operator.
  • The 223 Wylde is an ammunition chamber that accommodates the 5.56 NATO ammo and the .223 Remington.

What Is the Difference Between .223 and 5.56 Ammo?

An infographic showing the differences between the .223 Remington and the 5.56 rounds, facts, and their common uses.
The Two Rounds Appear Almost Identical, Making It Easy To Confuse The Two (Full image)

Although the difference between these two ammos is slight, its impact is huge and can affect a weapon’s performance, function, and safety. Let’s take a look at the major differences.


The major difference between the 5.56 and .223 is the pressure levels, where a 5.56mm NATO has a higher pressure level than the .223 Rem. The 5.56 runs at 58,000 psi, while the .223 runs at 55,000 psi.

You might say this doesn’t seem like much. But actually, the 3000 difference is quite significant, especially when it comes to weapon safety.

If we go by SAAMI standards, it means you can use a .223 in a 5.56 chamber, but you can’t use a 5.56 in a .223 chamber because it can lead to barrel rupture, damaging the weapon and injuring the shooter.


Fingers holding a bullet with a red tip

In terms of size, these two ammos are similar. The bullets feature the same diameter of 0.224 inches. The case and overall cartridge lengths are also the same at 1.76 inches (44.70mm) and 2.26 inches (57.40mm), respectively.

Because these dimensions are close, it’s easy to assume that a firearm chambered for one cartridge can chamber and fire the other one.

But no, that isn’t the case. I’d advise you to avoid that because of the difference in pressure I mentioned above. Stay safe and use the right ammo on the right rifle.


Leade is the gap between the cartridge’s mouth and the point where the rifling engages the ammo or bullet. The .223 Remington has a shorter leade than the 5.56. This means the distance from the case mouth to where the rifling engages the bullet is shorter.

One of the benefits of a shorter leade is enhanced accuracy but at the expense of increased pressure and reduced velocity

On the other hand, the 5.56’s longer leade results in increased velocity with low pressure and reduced accuracy.

This ammo was intentionally created to be a military cartridge with increased velocity in mind. In the process, they discovered this feature also leads to increased reliability by allowing the buildup of materials like carbon without affecting the function of the rifle.


223 vs 556 bullet drop graph comparing several different brands and grains
Bullet Ballistics Of Popular .223 and 5.56 Rounds (Full image)

Before we get lost in all the differences, let’s talk about what really matters. Performance. After all, what’s the reason for buying a particular type of ammo if not for how it’ll perform in the field?

When comparing the performance of these two ammos, I’ve factored in accuracy, velocity, and energy. The 5.56 ammunition runs at a higher pressure, which helps it achieve higher muzzle velocities and energy levels. This then leads to a flatter trajectory and better performance.

In addition, the 5.56 features a longer throat compared to the .223 bullet. The difference is .125 inches, and although it may seem small, the extra space allows the bullet to hold more gunpowder, resulting in higher performance.


.223 Remington and its box

Put the .223 Rem and the 5.56mm cartridges aside, and you’ll hardly be able to identify any differences in their case. They both have the same case type, which is rimless, bottleneck, and are the same length. 

The difference between the two cartridges is that the 5.56 has a longer throat on the casing, which allows for extra grain powder to be loaded to give it a greater performance.


Money matters too, right? You’ll be happy to know that the 5.56 and .223 cartridges are almost similar in price. However, the 5.56 is slightly cheaper by a very small margin to make you factor in price when comparing these two.

That said, if you want ammo for target practice, consider the 5.56 because you will need to purchase a large volume of rounds. In such cases, the price difference will make sense to you. Other than that, these two rounds are often affordable compared to most types of ammunition.


Several bullets and soldiers 

Both 5.56 and .223 cartridges are often available in the market. However, a few factors like current demand, geographic location, and manufacturing trends may affect these cartridges’ availability.

It’s common to find one cartridge more available than the other at a particular time. That said, hardly have there been reports that one type of cartridge isn’t available in the market. 

If you can’t find it at your local gun shop, check online retailers, as they’re likely to have them available.


.223 REM bullet and its box

If you’ve been in this sport for a bit already, perhaps you’ve heard people say before that a skilled shooter is accurate no matter the ammunition they’re using. And to some extent, they’re correct. 

But what if all factors remain constant? Well, the .223 cartridge boasts superior accuracy and a lot of that comes down to its leade or freebore, which we touched on earlier.

Specifically, the .223 chamber features a shorter leade with a more pronounced angle, and typically, chambers with shorter freebores and steeper angles yield better accuracy. 

But it’s worth noting that the 5.56mm chamber’s leade is longer than the .223’s by a mere .125″. It’s this subtle difference that gives the .223 its edge in accuracy.


NATO bullets inside and on top of a magazine

In terms of magazines, there really isn’t any difference between the two cartridges. A magazine designed for 5.56 cartridges can also work with .223 ammunition. This is because these two ammunitions are identical in terms of case dimension and bullet diameter.

Aside from that, the AR-15 platform, which is commonly used for both 5.56 and .223 rifles, has a standardized design that accommodates both rounds. In fact, you may find some magazines marked as ‘5.56/.223, indicating they hold both cartridges.

In terms of capacity, magazines can hold various numbers of rounds, from 10 to 20 to 30. Here, your option will depend on your preference and the legal restrictions in your jurisdiction.


223 Remington vs 5.56 cartridge specs comparison table
Differences Between The Two Rounds’ Specs

There is very little difference between these two when it comes to weight, seeing as both ammunition have the same bullet length and diameter. That said, the weight of a specific ammo will be determined by several things, including bullet and powder charge.

Bullet weights often vary with options like 55, 60, 62, and 77 grains for both 5.56 and .223 ammunition. Obviously, the higher the grains, the more the bullet will weigh. 

Plus, the amount of gunpowder will also contribute to the weight of the ammo. And with the 5.56 being packed with more gunpowder, it has a slightly higher cartridge weight than the .223 Remington.

Which Is Better, 5.56 or .223 Remington?

Since these two ammunitions are similar in most things, can we say one is better than the other? Well, it will depend on the application at hand. Take a look at these two applications.

Which Is Better For Hunting?

The .223 Remington is better for hunting than the 5.56. A few shooters may say it’s not ideal and that there are better ammo out there. They’re right, but in this case, remember we are comparing it to the 5.56 NATO cartridge.

The .223 Remington is lighter with less recoil and capable of taking down small to medium game. Although it was originally developed as a military cartridge, civilians have come to enjoy its uses in the field of hunting. (Source: .223 Remington)

Which Does the Military Use?

5.56 NATO bullets inside a magazine and its box

The military uses the 5.56 ammunition for its rifles. While it’s similar to the .223 Remington, they prefer it because it’s loaded to higher chamber pressures. This feature makes it handy in combat settings.

High-pressure ammunition generates high velocities, which translate to more energy directed to the target, causing serious wounds.

The high energy also results in a flatter trajectory, contributing to better performance, especially at longer distances. Since the military engages some of its targets at longer distances, they want ammunition that will deliver in such instances.

Can .223 and 5.56 Rounds Be Used Interchangeably?

Most of us have had this thought, ‘Since these two ammos are similar, why not use them interchangeably?’. 

In short, no, they’re not completely interchangeable.

.223 Remington bullets and its box

While we tend to treat these cartridges as interchangeable, the practice isn’t always advised. Let me explain. You can shoot .223 Remington ammunition in a 5.56 chamber, but you can’t shoot 5.56 ammunition in a 2.23 chamber.

Again, this circles back to the difference in pressure. The problem with firing a 5.56 ammunition in a rifle chambered for a .223 ammunition is the pressure spike

The 5.56 ammo’s normal pressure is 58,000 psi, and the .223 normal pressure is 55,000 psi. That 3,000 difference makes a significant impact.

The excess pressure level might damage the rifle or cause the primer to blow out of its pocket, messing with the internal workings of your rifle. Watch out for signs of excess pressure, such as cratered, flattened, or blown primers, as they indicate you are using the wrong ammo.

5.56 NATO barrel and bullets inside a magazine

How about the other way? It’s safe to shoot a .223 Remington ammunition through a rifle chambered for 5.56 ammo. But just because it’s safe, it doesn’t mean you should. Chances are that you’ll experience a poorer performance when you do that.

The .223 Remington has been designed for a tighter chamber and lower pressure for improved accuracy. When you put a .223 into a 5.56 chamber, the longer freebore will reduce the chamber pressure automatically.

This can lead to reduced pressure at the gas port, translating to less pressure to cycle your AR15 rifle properly. Most shooters argue that they hardly notice the difference in performance, but after a few rounds, you’ll notice something is off. (Resource: 5.56 Ammo)

As you can see, it’s better to use the right ammunition with the correct chamber. Also, considering that both these ammos are readily available in the market and are cheap, why not use the right one for your rifle?

5.56 vs 223 Remington: How Do I Know Which I Have?

Headstamp of .223 REM bullets

On several occasions, I’ve scratched my head, wondering which ammunition is before me because, to be honest, they look very similar. Here’s how you’ll know what you have.

Let’s start with the 5.56. Since it has roots in the military, there’s plenty of military ammunition in the market. Ammunition packaged as SS109, M855, and M193, and their variations, such as XM855 or XM193, are 5.56mm.

But how about if you’re using a friend’s ammunition, and they lost the packaging? Don’t worry. Look at the headstamp located at the base of the bullet. 

If it says ‘5.56x45mm’ or you notice 2-3 letters or numbers like ‘LC 13’, then this bullet meets military specs requirements, meaning it’s a 5.56 ammo. It’ll also usually have the NATO insignia stamped in.

On the other hand, if the headstamp reads 223 Rem, you know you have a .223 Remington round. In addition, most self-defense and hunting ammunition manufactured for civilians are often .223 rounds. 

Good examples are Hornady’s Varmint Express, Winchester’s Super-X, and Nosler’s Varmageddon. Keep in mind, though, that this isn’t always the case, and it’s better to err on the side of caution and confirm with a professional what you have.

What Is the .223 Round?

The .223 round is an ammunition designed by the U.S. military. Primarily used among civilians, it’s popular for sporting uses. How about a quick history lesson of where this ammo comes from?

History of the .223 Remington

The .223 Remington was first developed in 1957 as a military cartridge. After years of experimentation, in 1962, Remington Arms submitted the final design to SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute).

This cartridge was developed from the .222 cartridge, with the .223 having an elongated cartridge case and a shorter neck. These changes allowed the .223 to have more powder charge than its predecessor. 

Now, the original .223 Rem ammo adopted by the military was called M193 and fired a 55-grain bullet at a 3,260 muzzle velocity with a 1,294-foot-pound muzzle energy. It was capable of accurately hitting a target up to 500 yards. 

It was also released to civilians a year before the US Army could start using it. Many varmint hunters loved it for its extreme accuracy, low recoil, and low pressure. In fact, it outperformed the .222 in all aspects.

Before long, many firearm manufacturers were offering bolt action and semi-auto rifles in .223 Rem cartridges. Some of these rifles included:

  • Remington 700
  • Sako TRG
  • Ruger Mini-14
  • Ruger Hawkeye
  • Savage Axis
  • AR-15

The .223 Remington served the US Army until around 1980, when the FN Herstal company came into the picture, bringing better ammo for military purposes. Today, the .223 ammo remains popular among civilians, especially varmint hunters.

What Is the 5.56 Round?

The 5.56 is the 5.56×45 mm NATO cartridge, which is the standard cartridge used by the US military. The ammo is used on military rifles like the M4 carbine and M16. Let’s delve into the history of the 5.56 round.

History of the 5.56mm Round

In 1980, FN Herstal, a Belgian company manufacturing firearms and ammo, submitted its SS109 5.56x45mm cartridge design to NATO. This SS109 fired a 62-grain bullet at a 3,100 muzzle velocity with a 1,325-foot-pound muzzle energy.

Even though the 5.56 NATO cartridge was similar to the .223 Remington in dimensions, the former could handle a higher pressure.

That said, there were a few complaints regarding the adoption of this round because of battlefield reports that indicated less effectiveness regarding accuracy, stopping power, and effective range. This led to a few advancements of this ammunition.

Bullet boxes beside a gun on a wooden surface

One of the major complaints of the SS109 was about its inability to fragment or yaw. The M193, which was the .223 Remington ammo adopted by the military, could fragment, causing severe damage to the target.

The next iteration of this 5.56 NATO round was the Mk62, which the Special Forces immediately liked for its better terminal ballistics. That said, it wasn’t adopted widely because of the increased cost of the bullets.

As the 5.56mm NATO cartridge kept evolving and being improved, next was the Mk 318, which featured an open tip to cause soft tissue damage and a strong brass penetrator base, increasing its barrier penetration abilities. This allowed it to be used even on targets with body armor.

The latest iteration of the 5.56 ammunition is the M855A1, which was developed for a more noble reason. The US military wanted an eco-friendly option by moving away from bullets with lead cores. Aside from that, it has other advantages, such as being more accurate, increased wounding ability, and improved barrier penetration capabilities.

What Is .223 Wylde?

Man shooting at the target with a .223 Wylde

In the past, an AR-15 rifle would only come in two chambers, which was either a 5.56 or a .223. A genius by the name of Bill Wylde sat down and thought to himself, ‘Why not give people the best of both worlds?’ And he did, giving us the .223 Wylde.

First, understand that the .223 is a chamber and not an ammo. Wylde decided to create a hybrid chamber that would allow barrels to safely shoot the 5.56 NATO and the .223 Remington rounds with accuracy.

This new chamber had the external dimensions and leade angle of the 5.56mm cartridge and the leade diameter of the .223 ammo.

The .223 Wylde is basically an upgrade for any bolt action or AR-15 rifle. Does that mean you need to buy this .223 Wylde? Not necessarily, unless you want to. The barrel you already have is good enough as long as you use the correct ammunition.

Frequently Asked Questions

What is a bullet leade?

A bullet leade is the gap between the cartridge’s mouth and the point where the rifling engages the bullet.

Why does the 5.56mm NATO have a longer leade?

The 5.56 mm NATO has a longer leade as it was originally designed for military use. The leade ensures the cartridge chambers and fires reliably, even in less-than-ideal conditions.

Can an AR 15 223 shoot 5.56 ammo?

An AR 15 .223 can shoot 5.56 ammo, but it isn’t advisable since it has a lower chamber pressure. Using 5.56 ammo, which is loaded for higher chamber pressure, can lead to a pressure spike that damages the rifles.

Is 5.56 more powerful than 223?

5.56 is more powerful than 223 because it’s loaded to higher chamber pressures, unlike .223 Remington.

Is 5.56 and .223 the same bullet?

5.56 and .223 aren’t the same bullet. While similar in shape and bullet diameter, they have a few differing characteristics that make them two different ammunitions.


  1. Jeff Wood, Is .223 Remington a Good Round for Deer Hunting? Retrieved from https://www.guns.com/news/hunting-deer-223-remington-bullets-ammo
  2. Jo Deering, How Bad Is It… to Mix Up 5.56 and .223 Ammo? Retrieved from https://www.nrawomen.com/content/how-bad-is-it-to-mix-up-5-56-and-223-ammo/

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