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.223 vs 5.56 NATO vs .223 Wylde: Will Your Gun Blow?

Want to quickly know the difference between .223 vs 5.56 and potential safety concerns? We cover both plus .223 Wylde so you'll know the best for your gun.

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What’s the difference between .223 Remington and 5.56x45mm NATO?  

Do you know?

They’re basically the same right...or are they? Will my gun blow up if I get it wrong?

You might be thinking about purchasing or building an AR-15, or even a bolt-action or single-shot rifle in one of these calibers and find yourself understandably confused.

Faxon Firearms Ascent AR Pistol
Faxon Firearms Ascent AR Pistol

Worry not, we’re here to help.

It turns out .223 Remington, 5.56x45 NATO, and even the oddball .223 Wylde have a lot in common, but the differences are important.

PSA .223 Wylde Testing
PSA .223 Wylde Testing

So, let’s talk about it. We'll run you through the calibers and what sets them apart. Ultimately, you'll have a better understanding of .223, 5.56, and .223 Wylde.

What is Safe, What Isn't?

223 Rem 556 Nato 223 Wylde Table

So What’s the Actual Difference?

In a word...pressure.

Or at least the possibility of pressure.

The .223 Remington was designed as a civilian cartridge. But, when the U.S. military showed interest in it and after NATO started testing it, they increased the pressure of the cartridge to improve reliability in the newly designed AR-15.

PMC Bronze .223 55gr
PMC Bronze .223 55gr

As with many things, it's what’s on the inside that counts.  

Even though the case and projectiles may be identical, the pressure difference between .223 and 5.56 NATO makes it inadvisable to shoot the 5.56 NATO out of a .223 chamber.

In a .223 chamber, the 5.56 NATO round doesn’t have that extra room to stretch its legs. Thus it starts building pressure sooner.  

The increased pressure creates unsafe pressures, which can cause catastrophic failure.

catastrophic failure
We don't know what happened to this AR-15, but discribing it as a "catastrophic failure" seems fitting.

I don’t know about you but “catastrophic failure” isn’t a phrase I want to be associated with my firearms.

Going the other way, a .223 in a 5.56 NATO chamber is 100% safe -- just not as quite accurate as .223 ammo in a .223 chamber.

Choosing Between the Two

In years past, you had the option of getting an AR-15 in either .223 Remington or 5.56 NATO from most of the major builders.

But these days, basically every AR-15 on the market will be in 5.56 NATO or some other cartridge entirely like 6.5 Grendel, .300 Blackout, etc.

If you want a .223 Remington rifle, you'll normally have to go the bolt-action route or get a barrel for your AR separate from the rifle.

AR-15 Barrel Profiles
AR-15 Barrel Profiles

But, why would you do that?

Accuracy.

Faxon 14.5 Pinned Pencil Accuracy Tests
Faxon 14.5 Pinned Pencil Accuracy Tests

If you want a REALLY accurate rifle, then .223 is the way to go. But the applications for this rifle are normally limited to punching paper and sometimes hunting varments.

For the vast majority of people, an AR-15 in 5.56 NATO is going to be the gold standard.

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.223 Wylde: Best of Both Worlds

It really shouldn’t have taken as long as it did for somebody to look at the .223 chamber, look at the 5.56x45 chamber and go “Hey, you know what? I can make one version that’s better than both of them.”

Bill Wylde looked at the two chamberings and came up with a Goldilocks design that truly is the perfect middle-ground.  

He designed a chamber with the leade angle and external dimensions of the 5.56, but the leade diameter of the .223.

223 vs 5.56 vs 223 wylde
Chamber dimensions of the .223 Rem vs 5.56 NATO vs .223 Wylde

This gives you a chamber where the gas expansion is tight and controlled because of the smaller leade diameter of the .223. But also one you can fire 5.56 through because of the 5.56-style leade angle and length.

In practical terms, this means that both 5.56 NATO and .223 Rem ammo perform equally well in the .223 Wylde chamber.  

BA Hanson .223 Wylde Testing
BA Hanson .223 Wylde Testing

That said...the juice isn't really worth the squeeze.

Yes, .223 Wylde is more accurate than 5.56 NATO. And yes, it can fire both .223 and 5.56 NATO completely safely.

PSA .223 Wylde Accuracy
PSA .223 Wylde Accuracy

But with the ability to create sub-MOA AR-15s in 5.56 NATO, the accuracy gain presented by using .223 Wylde really isn't very much.

And almost never worth the price hike you'll normally pay. 

Best .223 Remington and 5.56 NATO Ammunition

First off, there is no such thing as .223 Wylde ammo. It's a chamber...not a cartridge. (Like the blinker fluid of the AR-15 world...)

With that out of the way, these are some great ammo choices for you that DO exist!

1. American Eagle XM193 55-grain

A great 5.56 round that is the classic 55gr ammo, perfect for plinking, training, or taking a class with.

American Eagle XM193 55gr
Prices accurate at time of writing

2. PMC Bronze .223 55-grain

Good quality .223 ammo, still plinking ammo but also good when reliability is important.

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3. Federal Gold Match 69-grain

Need .223 that is accurate? Federal Gold Match has you covered. They know how to make accurate ammo while still keeping the prices reasonable.

4. Wolf .223 Polyformance 55-grain

This is the truly budget stuff.

The steel-cased ammo isn't allowed at all ranges so check the rules before bringing it out the first time. That said, it always goes bang (for us at least) and is dirt cheap.

5. Speer Gold Dot Duty .223 55-grain

Speed Gold Dot Duty is a gold standard in defensive ammunition, this is what we load in most of our home defense AR-15s.

Conclusion

Hopefully, we answered all your questions about the differences between .223 Remington, 5.56x45 NATO, and .223 Wylde.

PMC X-TAC 5.56
PMC X-TAC 5.56

I know it's confusing at first, especially if you’re new to the debate, but this should give you get you started when choosing the best chambering to meet your needs.

Or you can do what I did and pick up one in each flavor and call the debate settled.

What's your preference in the .223 Rem vs. 5.56 NATO vs. .223 Wylde debate? Also, now that you know what chamber you want, take a look at our AR-15 Buyer's Guide to choose your rifle!

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Written By

Matthew Collins
Matthew Collins is a writer, editor, competitive shooter, hobby-level gunsmith and general firearms enthusiast. He has a background in the entertainment industry and currently works as one of our awesome writers in the field.

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Conversation

66 Comments

Join the discussion

  • 1
    I purchased a Colt AR15A3 a few years ago in .223. The guy that sold it was clueless about the differences in 5.56 and .223. I am so glad the differences are on the Internet in a variety of ways. Your tutorial is very informative. Thanks for the service.
    ...
  • It turns out that the first-gen Dodge Viper actually had blinker fluid. It’s real.

    For home defense I only use 5.56 in my Springfield Arms St. Victor, .223 for the range and plinking most of the time.

    Ex. Military so I tend to stay military
    ...
  • Can I swap out my .223 Remington barrel (16”) on my Howa bolt action rifle for a 24” .223 Wylde barrel? I’m not at all happy with the accuracy of 16” barrel.
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  • 1
    Having some work done to my old mini-14, it is chambered in .223. As part of the work I am rechambering it to WYLDE, primarily so as to be able to shoot whichever ammo I can find if it comes down to finding ammo.

    For my nickel, if you are buying a new rifle and you like the caliber hecks yeah pay up and get the WYLDE, then it doesn't matter.
    ...
  • 2
    For pew-pew purposes, having both 5.56 and .223 rifles in you gun locker or bailout box or zombie vault, is not out of the question. I just use the .223 rifle for my daily or accuracy. I also only stock .223 in the locker and box/vault. This way, they can all be used for any reason, at any time, without mistakes of catastrophic failure.
    ...
  • 3
    14
    Over the weekend I came across and add from Aim Surplus in which all of the 5.56 ammo was listed as 5.56/.223, or .223/5.56, even though the packaging was clearly labeled as 5.56 or as .223. I shot them an email (pun intended) about the fact that their marketing scheme was potentially dangerous since the 5.56 ammo should not be fired from a rifle chambered in .223. Their response was that they always label their ammo that way because they believe their customers are fully aware whether their rifles are chambered in 5.56 or .223 and will know which ammo they should use. Anyone else think that is a bad idea?
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    • paul aymond

      Yes I know the difference but I'm not new to firearms & ammo put 5.56 or 223 some people don't know the difference
      ...
  • 2
    7
    I had a 5.56 16” cmv 1:7 and could not get good groupings with 62 grain and higher 5.56 ammo. I switched to 18” 223 wylde barrel, 1:8, put some 77gr in it, and pegged 3 out of 5 within 1/2” in the bullseye. Seems to me like Wylde is worth it.
    ...
    • Snake Clark

      Indeed, Sir! I did that just a few years ago and have accuracy results that increase with the price of the ammo. No complaint with bulk 5.56 and get inside 0.5 @ 100 yd with better target stuff, and 0.5 with hunting ammo. Just rechamber!
      ...
    • Samuel Smith

      Perhaps the barel length, twist rate, and higher grain projectile had something to do with it
      ...
      • Stephen

        I fired the 77 gr out of both. I expected it to do better in the 1:7 twist 16” cmv 5.56 but it did not. The barrel length might have helped some but I would expect that to show up more at longer ranges.
        ...
    • Kelly Prophet

      Seems to me like getting a new barrel and completely different round was worth it...
      ...
      • Stephen

        “62 gr and above…”. The round wasn’t new. I tried the 77gr in the 16” cmv, too, with groupings over 1”
        ...
  • 2
    2
    Question? I am new to the AR-15 world, I've just built a AR-15, with the AERO-Precision Gen 2 Lower Receiver, Model X-15, and with a 223 Wylde 18" Barrel, Is it safe to shoot 5.56? Still learning!!, Thank you for your help..Clinton
    ...
    • Otherphone

      Why don’t you scroll up and read the article
      ...
    • Mark

      If you read the article you will see it is safe to shoot 223 and 556 in a 223 wylde barrel. Look at the chart above.
      ...
    • Mike

      Yes.
      ...
  • My Savage MSR 15 Recon is 223 Wylde and can be bought around the $800 range even during Covid high prices. It has free float barrel with 5 R rifling and is rated as one of the most accurate rifles out there up to $2,000 price. Check the online reviews, Guns and Gear, Sootch and many others. Use 62 or heavier grain as it has a 1:8 twist for best results. Love this rifle!
    ...
    • Daniel Cantrell

      Just bought a bunch of 556 loaded with 65 grain. Is it safe to shoot out of my AR15 with a 223 wylde barrel
      ...
      • Mark

        If you read the article you will see it is safe to shoot 223 and 556 in a 223 wylde barrel. Look at the chart above.
        ...
    • Daniel Cantrell

      I have a 223 wylde barrel on my ar15. I just bought a bunch of 556 loaded in 65 grain. Is it safe to shoot out of this barrel
      ...
      • Bob

        Yes it is safe to shoot out of a .223 Wylde barrel.
        ...
  • A 556 NATO will shoot the 5.56 x45 and the 223 Remington. 223 Wylde is just a chamber it is not an ammunition
    ...
  • 1
    I bought a wylde so in the case of civil unrest, I can pick up any 5.56 or .223 ammo and use it without worry. Is the extra money worth the peace of mind knowing it won't blow up in my face? To me, it is.
    ...
    • lakelandmusic

      I mean you really aren't going to blow up your gun if you have a 5.56x45mm barrel and shoot .223, just the reverse is true. You really want the 5.56x45mm for SHTF situation in the first place. .223 is more of a light hunting and target shootingcompetition cartridge. But I can see the allure being that it will shoot .223 more accurately, I just wouldn't want to be reliant on .223 as a combat cartridge.
      ...
      • Zerak

        you do realize there is almost no difference in performance of 5.56 vs .223 ?
        ...
        • Mike

          I would like to find an article with 2 identical rifles, 1 chambered in 5.56 and 1 in .223 Wylde. Both shooting PMC Bronze 55 grain .223 and comparing the accuracy at 100 yards. For decades I've know the difference between .223 and 5.56, but only in the last year have I heard that you lose accuracy shooting .223 out of a 5.56.
          ...
    • Michael Mullins

      You could have bought a 556 NATO and had the same advantages. They 556nato suits 556 x45 and 223 Remington. And it would also save you a little money. Remember, the 223 Wylde is just a hybrid of the 556 and 223
      ...