What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (2023)

Calibers can be confusing enough as it is. Range, power, muzzle velocities, stopping power and ballistics are all qualities of making the right decision of selecting a round.

An extremely popular choice is the 556 round. It comes from NATO dimensions and there is a civilian version to reflect that popularity.

Which then makes for an interesting question, with a variety of terms, what’s the difference between 5.56 and 5.56 NATO.

The term 556 in a civilian environment usually refers to .223 Remington round. 223 and 5.56 NATO have similar dimensions, but they have different chamberings and have different pressures. The .223 was designed for hunting and other civilian usages, while the 5.56 NATO is designed mainly for military usage.

People often think that the .223 and the 5.56 NATO rounds are interchangeable. Even though you can fire the .223 out of a 5.56 rifle, firing the 5.56 NATO out of .223 rifle can be dangerous.

What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (1)

Find out the critical differences between the .223 and 5.56 NATO, and how you can safely use each.

What Cartridges Are Described As 5.56*45mm?

The 5.56 * 45mm refers to two main cartridges, the .223 Remington and the 5.56 * 45mm NATO.

Often, when people talk about the 5.56, they are usually referring to the 5.56 NATO.

The .223 was first designed in 1957 as a rifle cartridge for commercial hunting.

The U.S. military also tested this cartridge when they took over the Armalite’s AR-15 to develop the M16 rifle. The U.S. Military later designed a 55-grain full metal jacket of the .223 for the M193.

The .223 was upgraded to a 62-grain full metal jacket designed to cause more damage. This updated version is the 5.56 * 45mm NATO we see today.

(Video) Is .223 or 5.56 Better?

The .223 was designed as a request by CONARC (U.S. Continental Army Command). They were looking for a bullet with supersonic speed at 500 yards, .22 caliber, a 20-rounds magazine, penetration of the U.S. military helmet at more than 400 yards, accuracy and ballistics similar to the M1 Garand, for a rifle that weighs at least 6 pounds.

Remington Arms, Fairchild Industries and several other engineers were involved in achieving this goal.

The .223 has an average diameter of 5.7mm and an average length of 45mm.

It also comes in different weights and varying velocities and strengths, with the pressure ranging from 55,000 psi to 62,366 psi.

What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (2)

What Does The 5.56 NATO Mean?

The 5.56 * 45mm (often referred to as the 5.56 NATO or 5.56) is an intermediate cartridge that was designed based on the .223 Remington.

It was named NATO since it’s the standard rifle cartridge design for NATO (North Atlantic Treaty Organization). But it’s still used by non-NATO countries.

Even though it was inspired by the .223, they have some considerable differences, as we’re going to discuss later in the article.

The 5.56 * 45mm is the second NATO standard rifle cartridge, after the 7.62 * 51mm larger cartridge.

Even though the 7.62 is larger and more powerful, it has powerful recoil, which made it difficult to selectively fire using the service rifles.

They had to replace it with a lighter, yet powerful cartridge. Currently, it consists of the SS1121, SS109, and SS110 rounds.

The 5.56 NATO has an average bullet length of 5.7mm and an average length of 57.40mm. The pressure ranges from 55,114 psi to 62,366 psi.

(Video) What Is The Effective Range Of 5.56?

When used in actual battles, the 5.56 NATO is known to have a lot of penetration and even cause a lot of damage to the human tissue. It’s designed to have a stable flight and impact a lot of hydrostatic shock, causing internal damage to the soft tissues.

In a battle, it’s not necessarily designed to kill, rather perversely. A wounded soldier often takes 3 to 4 other soldiers out of the battle as they tend to their fallen comrade.

However, the velocity of the bullet depends on the length of the barrel. If you’re using a shorter barrel, you may not achieve the ideal velocity to cause such damage.

Besides penetrating human tissue, ballistics tests have shown that it can penetrate 12mm into steel, even at 110 yards

What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (3)

Is. .223 Same As 5.56 NATO?

Even though .223 and 5.56 NATO looks similar, and you may find rifles that can fire both of them, they are different.

For instance, they both have the same capacity, but the 5.56 NATO has a thicker case, which allows it to handle high-pressure chambers. .223 has a shorter throat and a steeper angle than the 5.56 NATO.

The steeper angle and shorter throat increases accuracy, and pressure, but reduces the velocity. These specs are ideal for sporting activities.

The 5.56 NATO, on the other hand, has a longer forebore, which leads to a higher velocity. Also, 5.56 NATO releases more pressure than the .223. The testing methodology differs, but the most accurate test has shown that the 5.56 NATO has 5000 psi more pressure than the .223.

What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (4)

How To Identify A 5.56 Round

5.56 rounds often have the manufacturer’s code, the manufacturing date, and military headstamps.

The .223 Remington is often just labeled as .223 REM, and in some cases, the manufacturer’s name.

(Video) 5 56 NATO Wound Characteristics

Most of the 5.56 rounds have a stamped ring at the primer. This design was added by the U.S. Military to prevent the primer from backing out when firing a fully-auto rifle in battle. The .223 doesn’t have this crypt pocket.

What’s The Difference Between 5.56 And 5.56 NATO? - Aiming Expert (5)

You will see a NATO stamp on the cartridge.

What’s The Difference Between The .223 And 5.56 Nato?

As mentioned earlier, these two cartridges have similar dimensions. The main differences are the chambering and the pressure from both of them.

The .223 rifles’ chambers have a smaller loade and steeper angle to enhance accuracy at the expense of velocity.

The 5.56 NATO chambers have a larger loade and shallower angle to increase the velocity at the expense of accuracy.

These two cartridges also differ in terms of pressure. The testing may differ since the .223 is mainly a sporterized cartridge, while the 5.56 NATO is standardized for warfare.

The Dangers Of Mixing .223 And 5.56 NATO

You can easily interchange the two rounds for a rifle designated for the 5.56 NATO.

The chamber 5.56 chamber can handle a lot of pressure, and the .223 has less pressure. But some users claimed that firing the .223 on the 5.56 chamber reduced the accuracy of their shots.

But this seems to be determined by the rifle you’re using.

However, firing a 5.56 NATO in a rifle designated for the .223 could be dangerous.

(Video) 3A Body Armor vs. 5.56 Nato and 7.62 x 39

It causes the primer to jump out of the pocket, ending up in the rifle’s internal parts, damaging the rifle, or even injuring the shooter.

If you’re not sure if your gun is a .223 or 5.56 chamber, you can always check at the barrel side. Most manufacturers have labeled the rifles at the barrel, or the receivers.

You can also consult the seller.

Essentially, unless you are sure your firearm takes 556 NATO, don’t put the round in one that takes 223 Remington.

Final Thoughts

To be honest, the .223 and 5.56 NATO brings about a confusion that could have been avoided.

They are pretty much the same; the only difference is the pressure and the chambering.

The dimensions, looks, and designs are identical. If they created a universally acceptable cartridge, it would have been better.

To be on the safer side, you can always purchase a 5.56 rifle. That way, you can easily interchange the .223 and 5.56 NATO.

The difference between the two cartridges may be small but it’s important to know the difference.

The 5.56 NATO cartridge goes to a higher PSI than the 223 Remington, typically by 3000 to 5000.

The NATO cartridge also has a longer throat so more powder can be loaded, so you will get a bigger muzzle velocity from the round. That’s why it’s crucial to know if your barrel is capable of handling the round.

(Video) Is it SAFE to run a .223 through a 5.56 chamber? (223 -VS- 5.56)


Is 5.56 the same as 5.56 NATO? ›

5.56 is merely a number. 5.56 NATO is a specific caliber designation of a particular cartridge that has a nominal bore size of 5.56mm. While there are several cartridges that also have 5.56 as part of the designation, if someone merely says “5.56", they are almost invariably referring to the 5.56x45mm NATO cartridge.

What does 5.56 NATO mean? ›

The 5.56×45mm NATO round, pronounced "five-five-six", is an intermediate cartridge and the main bullet type used by guns made for NATO militaries. It was first used in the Vietnam War as the main bullet used by the US military.

What's the difference between NATO rounds and regular rounds? ›

The first difference is the higher pressure level of the 5.56 NATO cartridge which runs at approximately 58,000 psi. A 223 Remington is loaded to approximately 55,000 psi. The second and most important difference between the two is the fact that a 5.56 NATO chamber has a . 125” longer throat.

What type of 5.56 does the US military use? ›

The M855A1, a 5.56 mm Ball ammunition, is an enhanced performance round for today's combat and training environments. It works with the M4 Carbine, the M249 machine gun, and the H&K and M16A2 rifles.

Is 5.56 still the NATO round? ›

The 5.56 NATO round, however, wouldn't go on to be adopted as the standard for the alliance until 1980. Ultimately, the decision to shift from 7.62 x 51 mm ammunition to 5.56 x 45 mm came down to simple arithmetic. The smaller rounds weighed less, allowing troops to carry more ammunition into the fight.

Is 5.56 stronger than 9mm? ›

The 5.56 rifle cartridge is inherently more powerful than the 9mm pistol cartridge, so you might expect the 5.56 to be a lot louder than the 9mm, but that's not the case. They're actually pretty close to one another. The 9mm cartridge averages about 166 decibels while the 5.56 cartridge averages about 169 decibels.

Why is 5.56 Green Tip? ›

The US military adopted the round in the early 1980s to replace the M193 5.56 ammo in use at the time. It was renamed M855, and the tips were painted green so personnel could readily differentiate the new ammo from the old M193 rounds, which were gradually phased out.

What is the difference between a AR 15 and a AR 556? ›

AR-15-style pistols have much shorter barrels than typical rifles. For example, Ruger's AR-556 pistol models have barrels between 9.5 and 10.5 inches, or about half-a-foot shorter than its rifle cousin. A shorter barrel will reduce some muzzle velocity.

Why does NATO use FMJ ammo? ›

Most NATO militaries use only FMJ rounds. This is due to an international treaty that was signed many years ago that forbids the use of expanding rounds. However, the USA never ratified that section of the treaty, and the US Army just recently adopted hollow point ammo along with the new Sig Sauer® M17 pistol.

What round does the Russian military use? ›

The 7.62×54mmR rounds in use with the Russian Armed Forces are designed for machine guns and sniper rifles. As of 2003, there were several variants of 7.62×54mmR rounds produced for various purposes. All use clad metal as case material. A conventional steel-core bullet designed to engage personnel and weapon systems.

Is green tip 5.56 armor piercing? ›

Green-tip ammunition is most common in 5.56/. 223 Rem caliber and is mainly designed for use with the AR platform. These rounds were originally considered controversial, as they meet one of the criteria of the federal definition of armor-piercing ammunition.

Can I shoot a deer with a 556? ›

Federal offers 5.56/. 223 cartridges specifically designed for medium game, including the 55-grain Trophy Copper, the 62-grain Fusion MSR, the 60-grain Nosler Partition, and the 62-grain Trophy Bonded Tip. So, while the 5.56 NATO is a little underpowered for deer, it can still punch up to that level.

What will a 5.56 round penetrate? ›

The 5.56×45mm NATO SS109/M855 cartridge (NATO: SS109; U.S.: M855) with standard 62 gr. lead core bullets with steel penetrator will penetrate about 38 to 51 cm (15 to 20 in) into soft tissue in ideal circumstances. As with all spitzer shaped projectiles, it is prone to yaw in soft tissue.

What is the best 5.56 ammo for combat? ›

Best 5.56 Ammo
  • Winchester 5.56 NATO 55gr FMJ 200-round box.
  • Winchester 5.56 NATO M855 62gr FMJ LC 20-round box.
  • Winchester 5.56 NATO M855 62gr FMJ LC 1000-round box.
  • Hornady Black 5.56 NATO 62gr FMJ 20-round box.
Jun 3, 2022

What is the military replacing the 5.56 with? ›

The new weapon system will use the 6.8 mm family of ammunition instead of the 5.56 mm ammunition the M4/M16 utilized. The 6.8 mm has proven to outperform most modern 5.56mm and 7.62mm ammunition against a full array of targets.

Why use green tip ammo? ›

Green tip ammo is made to penetrate steel, which makes it very strong. The damage it can do is what makes it controversial for civilian use. This superior ammo was originally created to penetrate armor. It's considered dangerous by many, but nonetheless is legal to own in the United States.

What caliber does military snipers use? ›

The most popular military sniper rifles (in terms of numbers in service) are chambered for 7.62 mm (0.30 inch) caliber ammunition, such as 7.62×51mm and 7.62×54mm R.

What is green tip ammo? ›

Green tip ammo is made to penetrate steel, which makes it very strong. The damage it can do is what makes it controversial for civilian use. This superior ammo was originally created to penetrate armor. It's considered dangerous by many, but nonetheless is legal to own in the United States.

How far will a 5.56 shoot accurately? ›

General consensus holds that the 5.56 can consistently group shots at 1,000 yards. This is assuming you're using good ammo under ideal conditions – and also that you're not some ham and egger who just picked up a rifle for the first time last week.

Will a 5.56 round penetrate body armor? ›

Level/Type III Body Armor

Level III will stop most of all 5.56mm and 7.62mm bullets, but will not defeat military-grade armor-piercing ammo. For example, a NATO M855 5.56 x 45mm bullet with a 62-grain steel core will defeat a Level III armor system. It will, however, defeat a 5.56 x 45 mm bullet at 55 grain.

Whats more powerful 5.56 or 308? ›

Standard 308 Win loadings can still be combat effective out to 1,000 yards. By comparison, the 5.56 is typically only considered effective out to about 500 yards.

Is an AR-15 the same as an AR 556? ›

The Ruger AR-556 is a semiautomatic AR-15 style rifle manufactured by U.S. firearms company Sturm, Ruger & Co. Introduced in 2014 as an entry-level AR-15 using a direct impingement action, with variants since being released such as the upgraded AR-556 MPR (multi-purpose rifle) in 2017 and the AR-556 pistol in 2019.

Why can't you use 5.56 in a 223? ›

223 round is compatible with a 5.56 rifle in most cases. On the other hand, a 5.56 can significantly damage a barrel and chamber when fired from a rifle only designed to shoot . 223.

Can I shoot .223 in my 5.56 AR-15? ›

In summary: . 223 Remington ammunition may be shot safely in either a . 223 Remington or a 5.56mm chamber. However, you should only shoot 5.56mm ammunition in a rifle with a 5.56mm chamber or you are risking a potentially catastrophic (and dangerous) incident.

How far can a 5.56 bullet travel? ›

A standard FMJ 556 round could go up to 4000 meters (about 2.5 miles) or about 4375 yards. However, the effective range of the 556 bullets is around 800 yards in perfect conditions.

What is the smallest legal AR? ›

An AR-15 pistol has a barrel shorter than 16 inches — this is the minimum legal length for a rifle barrel. The National Firearms Act of 1934 (NFA) defines any rifle with a shoulder stock and barrel less than 16 inches in length and 26 inches in overall length to be a “short-barreled rifle” (SBR).

Does 5.56 hit harder than 223? ›

5.56 vs 223 Pressure Difference

The 5.56 NATO has a higher pressure than the 223 round and is one of the two major differences. The 5.56 NATO pressure is about 58,000 psi and the 223 round is approximately 55,000 psi.


1. 5.56 vs 7.62: Why the Military Still Uses 5.56 (Marine Reacts)
(Jamesons Travels)
2. 5.56 NATO vs .300 Blackout
3. 5.56 mm vs 7.62 mm AMMO - Which is the Better Long Distance Round?
(Survival Gear)
4. 🔴 The Actual Difference Between 5.56 And 223
(CRS Firearms)
5. Palmetto State Armory 16" Mid-Length 5.56 NATO AR-15 Rifle - Karen Hunter Review
6. What Distance Should you Zero your AR 15?
(Green Eye Tactical)
Top Articles
Latest Posts
Article information

Author: Patricia Veum II

Last Updated: 04/09/2023

Views: 6108

Rating: 4.3 / 5 (64 voted)

Reviews: 95% of readers found this page helpful

Author information

Name: Patricia Veum II

Birthday: 1994-12-16

Address: 2064 Little Summit, Goldieton, MS 97651-0862

Phone: +6873952696715

Job: Principal Officer

Hobby: Rafting, Cabaret, Candle making, Jigsaw puzzles, Inline skating, Magic, Graffiti

Introduction: My name is Patricia Veum II, I am a vast, combative, smiling, famous, inexpensive, zealous, sparkling person who loves writing and wants to share my knowledge and understanding with you.