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  • Post last modified:April 9, 2023

In this guide, let's break down 5.56 vs 223 in detailed specs. Both rounds are popular ammo for personal defense, target shooting and hunting. 

Here are their differences:

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223 vs. 556: Are They the Same?

While some shooters assert that the bullets are interchangeable, others refute these claims. Despite their similarities, the 223 performs differently from the 5.56 due to slight differences in its construction.


The 5.56 NATO bullet was created in the 1950s for use in the M-16 assault rifle. It became popular because of its effectiveness and easy handling. The 5.56 NATO round is a NATO standardized round, meaning it has been approved by the North Atlantic Treaty Organization for use by its member countries in military operations.

This standardization allows troops to easily share ammunition with allies, as they know the ammo will work with their weapons. It was an improvement over the 7.62 by 51 mm rounds used in the M-14 rifle, which were heavy and difficult to control.

Once the 5.56 was adopted by the military, Remington created a civilian version called the 223. So, the 223 is a civilian version of the military-grade 5.56 bullet."

Can You Load 223 Rounds in a 5.56 Magazine?


Rifle Chamber Safety


Shooting .223 out of a 5.56 chamber is safe, but it won't give you the best performance, especially if you use a bolt action rifle chambered for 5.56 NATO. On the AR-15 platform, 5.56 NATO rifles set up for higher recoil and pressure may struggle with .223 as it lacks the power to cycle properly.

For shooting both calibers in one firearm, choose the .223 Wylde. It's a hybrid rifle cartridge with a 5.56 NATO-angled chamber and a smaller freebore diameter for improved .223 accuracy compared to a traditional 5.56 chamber.

556 and 223 Meaning

223 - The 223 on a bullet's casing means its base has a diameter of .223 inches. It's important to follow the specifications of your firearm to determine which bullet size is suitable, to avoid damaging the gun. The "Rem" in 223 Rem stands for Remington, the company that first created the caliber in the 1960s.

556 - The 5.56 designation is used to describe a type of ammunition that is used in firearms chambered for 5.56mm NATO cartridges. It is similar in size and function to the 223 Remington round, but it is used in military weapons and has different specifications and performance characteristics. Most AR15 barrels on the market today are chambered in 556, so 223 can work in it.

223 vs. 556 Dimension

The 5.56 bullet has a higher pressure level of 58,000 psi, compared to the 223's 55,000 psi. According to SAAMI standards, you can use the lower pressure 223 in a 5.56 chamber, but you can't use the 5.56 in a 223 Remington chamber with lower pressure.

223 vs 556 dimension

The 5.56 also has a longer throat, which is .125 inches longer than the 223 Remington. This longer throat provides more room for gunpowder, making the 5.56 perform better than the 223.

The 223 bullet has tighter dimensions, which compensates for the pressure difference when fired from the same case. However, it has a smaller gunpowder capacity, giving it less power compared to the 5.56.

223 vs 556 Ballistics

M193 vs M855

The main difference between M193 and M855 5.56 rounds is that M193 has a 55g lead core surrounded by a copper jacket with a boat tail, while M855 has a 62g bullet with a steel core and a steel penetrator tip.

5.56 M855
federal m193 ball ammo

When deciding which one to buy, consider your shooting needs. For distances less than 100 yards, the lighter and cheaper M193 ammo gives better performance due to its higher velocity. But for longer distances, go with the M855 with the penetrator tip to combat wind-drift.

Keep in mind that M855 is more likely to tumble or "keyhole" upon hitting a target, causing it to penetrate less deeply and shift in unintended directions. This is especially important if you're using the rounds to hunt. A tumbling round may miss vital organs and destroy meat or rupture bowels.

It's easier to buy 55 gr rounds than 62 gr rounds, as the 55 gr is more widely available and produced in larger quantities. This makes it more accessible for those looking to purchase ammunition for their firearms. However, the choice between the two will ultimately come down to the intended use and personal preference, as the 62 gr rounds may be better suited for certain shooting scenarios, despite being less readily available.

223 VS 5.56 Bullet Weight

There is a wide range of options available for 223 and 556, including weights less than 50 grains. Reloaders, in particular, have the option to choose from a variety of bullet weights and even handload their own ammunition using the specific bullet weight they prefer. However, it's important to note that using lighter bullets may result in decreased accuracy and velocity, and that some rifles may not be compatible with certain bullet weights.

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Most of the bullets fired in the US are used for recreation, and in those cases, a standard 55-grain bullet should be fine. If you're looking for something more heavy-duty, Remington offers 77-grain rounds that are used by military marksmen.

223 vs 5.56 Stopping Power

stopping power

Referenced concealedcarry.com

The bullet energy creates the stopping power required to bring down your target. The .223 Remington has an advantage in this area, delivering higher energies at every distance, including at the muzzle. However, the difference between the two decreases at greater distances, with the .223 Remington delivering 296 ft-lb at 500 yards and the 5.56 trailing by just 27 ft-lbs at 269 ft-lbs at the same distance.

Though the .223 Remington boasts higher energy, the 5.56 NATO has a higher pressure and can be tough on your firearm over time. The 5.56 NATO's .125” longer throat accommodates approximately one extra grain of powder, accounting for the extra pressure.

223 vs 556 Accuracy

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Shooting both 223 and 5.56 bullet can cover distances over 1000 yards, but its velocity can decrease due to natural factors like gravity, wind, air, and the angle it is fired from. This means that beyond 400 yards, the bullet may not have as much impact on the target.

However, within the range of 400 to 500 yards, the 5.56 bullet will deliver maximum damage to the target. This makes it an ideal choice for battlefield use, allowing soldiers to accurately hit targets from a distance.

36 yard zero high height over bore result

The major impact that will affect accuracy and range are actually barrel length and bullet weight. The change in variables can change everything else.

If you want to improve your accuracy even further, consider using a magnified scope. A magnified scope allows you to see your target more clearly and precisely, giving you a better chance of hitting it. Whether you're shooting at the range or in the field, using a scope can make all the difference in your accuracy.