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

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?

i know what things are
We know you know…you know?

It’s okay if you don’t know.  

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.

Best Complete AR-15 on a Budget
at PSA

Prices accurate at time of writing

Prices accurate at time of writing

Worry not, we’re here to help.

It turns out .223 Remington, 5.56×45 NATO, and even the oddball .223 Wylde have a lot in common, but the differences are important.

Let’s talk about it.

What is Safe, What Isn’t?

 .223 Chamber5.56 NATO Chamber.223 Wylde Chamber
.223 RemYesYesYes
5.56 NATONoYesYes

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 US military showed interest in it and after NATO started testing it – they increased the pressure of the cartridge a bit to improve reliability in the newly designed AR-15.

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, and thus 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 is going to 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 bolt action or get a barrel for your AR separate from the rifle.

But, why would you do that?


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.

.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 5.56×45 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.

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.

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

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

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. 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.

.223 Wylde ammo is kind of 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 gr

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

Best 5.56 XM193 55 gr
at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

2. PMC Bronze .223 55 gr

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

3. Federal Gold Match 69 gr

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

4. Wolf .223 Polyformance 55 gr

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.

at Lucky Gunner

Prices accurate at time of writing

Prices accurate at time of writing

5. Speer Gold Dot Duty .223 55 gr

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

at Lucky Gunner

Prices accurate at time of writing

Prices accurate at time of writing

Parting Shots

I really hope that answers all your questions about the differences between .223 Remington, 5.56×45 NATO, and .223 Wylde.  I know it’s confusing at first, especially if you’re new to the debate, but this should give you everything you need to know to choose 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.

Now that you know what chamber you want, take a look at our AR-15 Buyer’s Guide to choosing your rifle!

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37 Leave a Reply

  • Commenter Avatar
    Michael Mullins

    A 556 NATO will shoot the 5.56 x45 and the 223 Remington. 223 Wylde is just a chamber it is not an ammunition

    December 21, 2020 7:32 pm
  • Commenter Avatar
    Dan Murphy

    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.

    November 29, 2020 12:29 pm
    • Commenter Avatar
      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

      December 21, 2020 7:16 pm
  • Commenter Avatar

    can a 5.56 nato ar-15 shoot .233 wylde

    November 3, 2020 12:02 pm
    • Commenter Avatar
      David, PPT Editor

      .223 Wylde is a chamber, not a cartridge. Wylde chambers can shoot 5.56 and .223!

      November 3, 2020 12:12 pm
      • Commenter Avatar

        It is the best of both worlds just read about it’s creation

        May 18, 2021 3:26 am
    • Commenter Avatar
      Michael Mullins

      A 556 NATO will shoot the 5.56 x45 and the 223 Remington. 223 Wylde is just a chamber it is not an ammunition

      December 21, 2020 7:18 pm
  • Commenter Avatar
    Charles Cottrell

    I have a bushmaster xm15 es2 and it is stamped 5.56 nato on barrel. Can I fire .223 Remington through it safely?

    June 17, 2020 5:29 pm
    • Commenter Avatar
      David, PPT Editor


      June 18, 2020 12:50 am
    • Commenter Avatar
      Michael Mullins


      December 21, 2020 7:13 pm
  • Commenter Avatar

    On their website, Seekins Precision makes more than a few AR’s chambered in .223 Wylde. That’s how I became aware of, and curious about .223 Wylde. Thanks for the in depth explanation of Wylde, and including the difference between 5.56 and .223. My rifle is 5.56 NATO - so I’m good to go.

    May 1, 2020 9:15 am
  • Commenter Avatar

    I recently build two AR15 carbines using kits i bought from a prominent online provider. One was a standard 16" 5.56, and the other a 18" 223 Wylde, and the cost for each kit saw almost the same, $329 and $359 respectively. That was before COVID 19 issue, so prices now may very, but my point is there wasn't much cost difference and the 223 Wylde has a full SS barrel. This was a great reference article when deciding what to buy. THANKS

    May 1, 2020 7:54 am
  • Commenter Avatar

    Can my GALIL .223 safely use MAGHTECH/CBC 5.56 M193 NATO 55 GRAIN FMJ ammo which is widely available?

    March 25, 2020 2:03 pm
  • Commenter Avatar

    The cartridges listed above are plinking quality. Far from a match or best. M262 Mod 1 from Black Hills is phenomenal up to and including 500 yards and if the wind isn’t significant can do very well at 600 yards in a match AR.

    September 1, 2019 9:36 am
    • Commenter Avatar


      The first sentence should have stated: The cartridges listed above are mostly plinking quality, with the exception of Federal Gold Medal and Speer.

      Also, I should have added to take advantage of heavier bullets a slow twist barrel is ideal.

      September 1, 2019 9:43 am
  • Commenter Avatar

    Thanks for the info. I'm new to this rifle business. Now I think I can start making a decision on a long gun.
    Maybe some day you could do a review of the rifle caliber pistols of today.


    April 12, 2019 7:32 pm
  • Commenter Avatar

    Well, not worth the extra money? Faxon Barrels are great and affordable not only are they .223 Wyld but also 5R. So much for trying to turn people off the Wylde barrels.

    April 12, 2019 11:53 am
  • Commenter Avatar
    Bravo Tango

    Sorry, fella, but you can't just say that certain ammo is more accurate than another. For instance, my 20", 5.56 barrel, with a 1:7 twist doesn't like any 55 gr. ammo that I've tried with it. Noted, I have only used factory ammo. A 55 gr. handload tailored to it might shoot well. I am not yet into handloading. What my particular barrel does like is Hornady 5.56x45mm NATO Frontier HFR320 75 gr HPBT, which is only $0.48 per round at Outdoor Limited. I can, and have shot many clover leaves with it. The best groups that I have shot were just under 1/2 inches, I am almost always less than 3/4, with the occasional flyer.

    I think that I am forced to agree with "Mark", in his remarks, when he says that y'all must be getting kickbacks from the ammo manufacturers that you list as most accurate. I personally don't mind if you are receiving sponsorship monies from anyone. I do have a problem when it affects your partiality during an article. If you are going to accept money from manufacturers, you should tell the manufacturer up front that their support will not affect your partiality and, if their products don't hold up to snuff, not to be surprised if they don't get mentioned in your "best of" lists, or that they get called out on a lack of quality. If they do get called out, let them know that it is just a call for them to step up their game.

    If you are not letting sponsorship monies affect your partiality, then you definitely need to get much more detailed about all the underlying conditions that were met for you to make certain assessments. To be honest, this is not the only article from Pew Pew Tactical that has made me think that your product assessments are influenced by a need to please your sponsors. I wouldn't be surprised if there are many others that have the same perceptions that I do. If you want to be taken seriously, you need to make sure that this perception is eliminated. I would hate for you to lose followers over misconceptions.

    April 12, 2019 10:31 am
    • Commenter Avatar
      David, PPT Editor

      Thanks for the feedback.

      We don't have sponsors, Federal or any other manufacturer or retailer had no involvement in this article.

      It is also very easy to state that some ammo is more accurate than others, consistency and quality control goes a VERY long way in creating accurate ammo. In our testing, Federal Gold Metal has performed very well in a wide variety of calibers and weights. While results will very depending on barrel, brand, weather, shooter skill, etc.

      That said - the article does not say that X ammo is more accurate than Y ammo. It simply stated that Federal Gold Metal is an accurate option.

      April 12, 2019 11:10 am
      • Commenter Avatar


        August 2, 2019 12:56 pm
        • Commenter Avatar

          You may not wear your ego on you sleeve but you do type in all caps and that alone is just down right unethical in and of itself....

          September 27, 2019 10:52 pm
  • Commenter Avatar
    Peter Post

    I have heard that a bolt gun chambered in .223 can safely withstand the pressure of a 5.56 cartridge. Is this true? I'd like to add a Ruger predator to my safe but I don't want to worry about swapping ammo between the bolt gun and my AR. Or... can the Ruger barrel be changed out for a 5.56 chamber?

    April 12, 2019 6:44 am
    • Commenter Avatar
      David, PPT Editor

      Bolt guns are normally rated for higher pressure, but I would ask Ruger to be sure.

      April 12, 2019 7:51 am
    • Commenter Avatar

      I realize this is a bit late. When the 223 came out, it was a result of the military adoption of the 5.56x45 for the M-16. It was reported back then that the 5.56 was a little higher pressure round than the 223. This was also reportedly different because of where they tested the cartridges peak pressure(the 5.56 at the mouth of the cartridge and the 223 on the body of the cartridge). I started shooting the 223/5.56 in the late 60's and have yet to see a 5.56 blow a 223 chamber. Hell, back then, no one really knew the difference. It was like firing surplus 30-06 ammo in a civilian 30-06. The 5.56 ammunition was good plinking and practice ammunition. If you ever see an instance where a 5.56 blows a 223 action, you might find out there was more to it than the wrong cartridge. Usually an excuse for bad reloading practices.

      April 25, 2020 12:58 pm
  • Commenter Avatar

    Just go with 5.56 chamber and you are gtg to use .223 as well.

    April 12, 2019 4:10 am
  • Commenter Avatar

    Saw a 5.56 AR-15 That fired a .300Blackout. It did not look anything near as bad as the picture above. Not good that a 30 cal will even chamber in a .224

    April 11, 2019 8:51 pm
  • Commenter Avatar

    You guys must be getting a Kick-back from Federal; everyone who has tried American Eagle gets 3.5-4" groups at 100 yards. I shot about 50 rounds of it through a new rifle and almost threw the rifle out. I had some hot home loads for my bolt action and tried them, and my groups went from 4" to less than 3/4 inch instantly. No more factory ammo for me. That failure that you you picture in your article may have been due to 5.56; but only if following a squib with one.

    I have done a lot of research into the difference, the standard chamber drawings show a slightly longer jump to the rifling for 5.56.
    Standard cartridge dimensions for .223 and 5.56 are identical; the difference is in the wall thickness of the case (MIL spec is thicker; therefore less internal volume; therefore potential for higher pressure with an identical load).

    Likewise, heavier bullets are longer, so at the same COAL, there will be less volume in the case; again more potential for higher pressures. Also with heavier bullets; they may have steeper ogives with the possibility of a standard length bullet contacting the rifling when chambered, causing an over pressure condition.

    To have that level of catastrophic failure, you need to really screw up a lot more than one vs the other.

    Wylde Chambers have proven no advantage to accuracy, and many have not chambered heavy 5.56 or heavy home-loads. In my experience most .223 chambers will chamber ammo that will not chamber in the Wylde barrels. Are most manufactures over reaming their .223 for safety? Maybe.

    April 11, 2019 4:43 pm
    • Commenter Avatar
      Brian J

      There is no difference in wall thickness. They are the same case.

      April 11, 2019 10:43 pm
      • Commenter Avatar

        NATO 5.56 case wall thickness is not the same, it’s thicker. Lake City is a noted example. Externally both 223/556 are identical but internally there is slightly less volume available.

        April 12, 2019 6:27 am
    • Commenter Avatar

      I usually average 1.5-2MOA with American Eagle. As for Wylde/556/223 barrels you are wrong. If you reload, especially for bolt action you probably aren’t full length resizing the cases. That’s most likely why your examples will chamber in one rifle and not the other. 5.56 has the loosest chamber.
      As for Wylde it is well known for greater accuracy even with heavier bullets in factory loads. Any chambering can shoot better than another with a random reload. Reloaders can tailor a load for a specific barrel, I’ve done it for years.

      April 12, 2019 6:43 am
    • Commenter Avatar
      David, PPT Editor

      Thank you for the feedback.

      No manufacturer or retailer had any involvement with this article.

      American Eagle normally groups 2 MOA for me, that is consistent with other brands offering this variety of ammo.

      The picture was only an example of a catastrophic failure, it is not credited to any specific event. We mention that in the caption of the picture.

      April 12, 2019 11:13 am
  • Commenter Avatar

    Why is Speer Gold Dot Duty .223 55 grain a gold standard in defensive ammunition? Versus other brands producing similar ammunition...

    April 11, 2019 4:04 pm
    • Commenter Avatar

      I actually prefer Hornady TAP but I know Speer has had almost a monopoly in law enforcement for decades.

      April 12, 2019 6:11 am
  • Commenter Avatar
    Graham C Taylor

    Great Article - maybe should have read before I spent loads of time researching the best 223 Wylde Upper and therefore the most expensive :-) However. A request. When comparing ammo prices could you make it a per round or per 100 deal and keep the playing field level? Thanks!

    April 11, 2019 4:02 pm
  • Commenter Avatar
    Shepherd of Fire

    Maybe it is because .223 Wylde complete rifles tend to be a tad bit pricier at most retailers.

    April 11, 2019 11:58 am
  • Commenter Avatar

    Hmm haven't really noticed a huge price difference NATO and Wylde barrels. Not really much of a difference if any at all really.

    April 11, 2019 8:20 am
    • Commenter Avatar

      There was a considerable price difference 10+ years ago. Now Wylde barrels are extremely common even in budget builds for target and hunting rifles. Article is a bit out of date.

      April 11, 2019 10:24 am