exactly what is different between 5.56 and .223

[BANGBANGBOOM]

My friend is under the false impression that .223 and 5.56 rounds are exactly the same. I told him that he was incorrect but i am not articulate enough to convince him of the difference. I know that firing a 5.56 round from a rifle chambered for .223 rounds is not a good idea but the other way around is ok...? Maybe one of you knowledgeable folks could help me articulate exactly what the difference between these is. Thanks.

[bulletproof]

My friend is under the false impression that .223 and 5.56 rounds are exactly the same. I told him that he was incorrect but i am not articulate enough to convince him of the difference. I know that firing a 5.56 round from a rifle chambered for .223 rounds is not a good idea but the other way around is ok...? Maybe one of you knowledgeable folks could help me articulate exactly what the difference between these is. Thanks.

They are exactly the same besides the powder load and pressures they operate at. Think of 9mm vs 9mm Nato or 9mm +P.

[Shipyard]

$4 a box

[Stradawhovious]

Case wall thickness (affects internal case volume), and (sometimes) COAL.

The 5.56 is potentially a much higher pressured round, especially if you relaod 5.56 brass to the specs of a hot .223 cartridge. This is (to my understanding) the fuel behind the statement that it could be dangerous to fire 5.56 in a rifle chambered in .223.

I could be wrong.

I often am.

[bulletproof]

Case wall thickness (effects internal case volume), and (sometimes) COAL.

You're definitely wrong about case wall thickness. If you buy a lot of .223 you'll sometimes see them using NATO brass. Even lots of Lake City 5.56 brass vary on the case wall thickness and weight. I've actually seen where the exact opposite is true and the .223 Win cases have thicker brass than the 5.56 military rounds.

There may be something to be said about the COAL since the 5.56 chamber can utilize heavier bullets / tracers.

[JJ]

A 5.56 chamber will always have a longer throat than the 223. I guess the .gov decided that with the higher pressures, the bullets need a bit more run time.

[ijosef]

Does anyone have experience with the .223 Wylde chambering? I've read about it and it supposedly the "best of both worlds," but I've never heard any testimonials.

Here's an excerpt from the all-knowing Whack-a-pedia on the matter:

While the 5.56mm NATO and .223 Remington cartridges and chamberings are very similar, they are not identical.

While there is a myth that 5.56 NATO cases are thicker and hence have less capacity than commercial .223 cases, this has been shown to be false. Each brand of case and each manufacturing lot has a slightly different case capacity; 5.56 NATO and .223 commercial cases tend to have nearly identical case capacity when measured using the water test.[6] The NATO specification allows a higher chamber pressure. NATO EPVAT test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the location used by the United States civil standards organization SAAMI. The piezoelectric sensors or transducers NATO and SAAMI use to conduct the actual pressure measurements also differ. This difference in measurement method accounts for upwards of 137.9 megapascals (20,000 psi) difference in pressure measurements. This means the NATO EPVAT maximum service pressure of 430 megapascals (62,000 psi) for 5.56mm NATO, is reduced by SAAMI to 379.21 megapascals (55,000 psi) for .223 Remington.[7] In contrast to SAAMI, the other main civil standards organization C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56mm NATO.

The 5.56mm NATO chambering, known as a NATO or mil-spec chamber, has a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 Remington chambering, known as SAAMI chamber, is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber (Bill Wylde)[8] or the ArmaLite chamber, which are designed to handle both 5.56mm NATO and .223 Remington equally well. The dimensions and leade of the .223 Remington minimum C.I.P. chamber also differ from the 5.56mm NATO chamber specification.

Using commercial .223 Remington cartridges in a 5.56mm NATO chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223 Remington chambered gun due to the longer leade.[9] Using 5.56mm NATO mil-spec cartridges (such as the M855) in a .223 Remington chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[10][11] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56mm NATO, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56mm NATO ammunition.

[steve4102]

And there you have it!

The external dimensions between 223 and 5.56 are the same.
The 5.56 has a higher Max operating pressure.
Both share the same Max OAL of 2.260. The 5.56 is not longer.
That's it!

The rest is in the rifle/chamber not the ammo.

From Sierra.
The conventional wisdom to reduce loads with military brass is familiar to most reloaders and is generally good advice. The rationale here is that the military cases tend to be somewhat thicker and heavier than their civilian counterparts, which in turn reduces capacity and raises pressures. This additional pressure normally requires a one or two grain reduction from the loads shown in most manuals or other data developed with commercial cases. While this is most often the situation with both 308 Winchester and 30-06 cases, it is less true with the 223 brass. We have found that military cases often have significantly more capacity than several brands of commercial brass. Again, take the time to do a side-by-side comparison of the cases you are working with and adjust your load as needed. There may be no need for such a reduction with the 223. Know your components and keep them segregated accordingly.

Note the case capacities here, 5.56 has the highest.
http://www.6mmbr.com/223Rem.html

[MnHornet]

You should read this article from arfcom. http://www.ar15.com/forums/topic.html?b ... 300&page=1
Many advise against firing 5.56 in a rifle chambered in .223. I don't shoot mil ammo in my .223 chambered rifle.

[Teeldo]

Are you talking about [url=http:]distance between two cities[/url]? I mean i did not understand that what is 5.56 and .223. Can you explain me about it? I want to know about it. Is this about cities or any other things?

Bangladesh ip.....link broken

[grousemaster]

Are you talking about distance between two cities? I mean i did not understand that what is 5.56 and .223. Can you explain me about it? I want to know about it. Is this about cities or any other things?

huh?

[Pezhead]

Say what. Spam?
I shoot .223 in my 5.56 marked AR. Now if it was marked .223 I wouldn't shoot 5.56.

[Thunder71]

5.327