.223 or 5.56 mm

[LaVere]

Why would any one have different names and specs for nearly the same cartrage? If 5.56 was the first made why not have them all 5.56 mm. Maybe because I didn't think of it first. Or mine is one iota different. So you must use mine and not there's and buy from me.
Just crazy

 

[MachIVshooter]

If this irks you that much, the rebadging the automakers do must drive you absolutely crazy.

 

[LaVere]

Well as a matter of fact it does.

 

[gym]

I believe that the NATO designation is 556, and it "may" be loaded to a higher pressure than 223. That is the short version of what I got from reading about this stuff a couple years ago. Otherwise they are the same

 

[Steel Horse Rider]

One is the military description and the other is the civilian. I am sure an argument will soon ensure about the many urban legends involving interchangeability and the destruction of the weapons if the ammunition is interchanged.

 

[Hanzo581]

One is the military description and the other is the civilian. I am sure an argument will soon ensure about the many urban legends involving interchangeability and the destruction of the weapons if the ammunition is interchanged.

Sooo you can use a 5.56 round in a .223 chamber? I've always heard .223 in a 5.56 is fine but not the other way around.

If this is really just an urban legend then it must be one of the most popular gun myths ever because I read it all the time.

 

[CoRoMo]

Why would any one have different names and specs for nearly the same cartrage?

They have different names and specs because they are different. Nearly the same cartridge = different. Supposedly negligible differences are still differences. The minute variations between case walls, operating pressures, leade length, etc. can be presented as inconsequential, but they can't be demonstrated to be identical.

If 5.56 was the first made...

This is not the order in which they are recorded to have been designed. I've only ever read/heard that the .223 Remington preceded the NATO round.

http://en.wikipedia.org/wiki/5.56×45mm_NATO

The 5.56×45mm NATO (official NATO nomenclature 5.56 NATO) is a rifle cartridge... It is derived from, but not identical to, the .223 Remington cartridge.

Parent case.........223 Remington

 

[BradN]

http://www.luckygunner.com/labs/5-56-vs-223/

 

[rehorne]

Oh Crap, Not this again.. Why not start with the .308, 7.62x51 thread again.

 

[HexHead]

If it was only an urban legend, SAMMI wouldn't advise against shooting 5.56 in a barrel marked for .223.

See page 7...

http://www.saami.org/specifications...1-Unsafe_Arms_and_Ammunition_Combinations.pdf

 

[Working Man]

Here is a decent article in the American Rifleman that may help.

http://www.americanrifleman.org/articles/223rem-vs-556-whats-in-a-name

Copy and pasted below:

223 Remington Vs. 5.56: What's in a Name?

There is much confusion between the .223 Rem. and the 5.56 NATO rounds.

By Bryce Towsley (RSS)

March 04, 2013

Originally published September 2007

Most gun guys know the history of the .223 Remington and that it—like so many of our popular cartridges—started life in the military. Because the military switched to metric designations sometime in the 1950s, this little .22-cal. cartridge was later called the 5.56x45 mm NATO (commonly referred to as “5.56x45 mm”).

 

[HexHead]

5.56 chambers have a longer Leade than .223 chambers, as many military rounds have longer OAL than .223. Using those rounds in a .223 chamber can cause higher, unsafe pressures.

The brass is identical, you can reload 5.56 brass for .223. As someone pointed out when I asked about this, "you don't see 5.56 die sets".

 

[AWorthyOpponent]

Wikipedia is your friend....

They're different, although slightly. There are many different rounds that are similar, but different. 357 mag can shoot 38 special, etc...

http://en.wikipedia.org/wiki/.223_Remington#.223_Remington_versus_5.56_mm_NATO

 

[Queen_of_Thunder]

Sooo you can use a 5.56 round in a .223 chamber? I've always heard .223 in a 5.56 is fine but not the other way around.

If this is really just an urban legend then it must be one of the most popular gun myths ever because I read it all the time.

Using 5.56 in a .223 chamber is not safe. Do not use a 5.56 round in a .223 chamber.

 

[alsaqr]

Contrary to popular myth, most over the counter guns are not chambered by experienced gunsmiths. They are chambered by hourly labor at a rather low wage rate. The chamber you get depends on several factors; such as experience of the guy wielding the reamer, the attitude of the guy with the reamer, the condition of the reamer, etc.

What you think you know about .223/5.56mm ammo and guns may be wrong. This guy broke away from the pack and conducted some tests:

http://www.luckygunner.com/labs/5-56-vs-223/



Some of the boxes say .223 on the outside but the ammo inside is 5.56mm. A problem exists today that few have given any thought too. Much of the ammo sold today, be it called .223 or 5.56mm, has been rejected by the US military because it does not meet military specs. i've seen cases with necks that are more than .045" longer than spec. Jam that long neck into the leade and pressures do up dramatically.

Way back when the US military operated all the ammunition plants; ammunition that did not meet spec was burned or torn down. Today most of that ammo is being sold by the company that operates the ammo plant.

 

[Queen_of_Thunder]

Contrary to popular myth, most over the counter guns are not chambered by experienced gunsmiths. They are chambered by hourly labor at a rather low wage rate. The chamber you get depends on several factors; such as experience of the guy wielding the reamer, the attitude of the guy with the reamer, the condition of the reamer, etc.

What you think you know about .223/5.56mm ammo and guns may be wrong. This guy broke away from the pack and conducted some tests:

http://www.luckygunner.com/labs/5-56-vs-223/

The easy way to solve this is to shoot in a firearm what it says you shoot.

 

[wally]

Using 5.56 in a .223 chamber is not safe. Do not use a 5.56 round in a .223 chamber.

Links to actual events where doing proved a safety issue?

With people so lawsuit happy that you get end up in court for serving "too hot" coffee, the ambulance chasers would be salivating at the opportunity to sue the gun industry if there were any real world safety issues with 5.56 vs. .223 (or .308 vs 7.62 for that matter).

 

[CoRoMo]

+1 wally

Many of you need to read the article linked by BradN from top to bottom. Shooting 5.56 in a .223 chamber will certainly exceed SAAMI pressure maximums but it is relatively slight. That is not dangerous by default because rifle barrels aren't made with a rupture threshold at the SAAMI pressure maximum. They can take that slight bit of excessive pressure.

 

[denton]

Much of the ammo sold today, be it called .223 or 5.56mm, has been rejected by the US military because it does not meet military specs.

Yup. ATK operates Lake City under contract with the government. That's exactly what they do. Did a consulting gig there a while back. As far as I know, they do label all the boxes 5.56.

 

[Zoogster]

With people so lawsuit happy that you get end up in court for serving "too hot" coffee, the ambulance chasers would be salivating at the opportunity to sue the gun industry if there were any real world safety issues with 5.56 vs. .223

That is precisely why they put the warning.
Just like many gun manuals say not to reload even when they are little different from other guns.

We are in a time period when warnings are no longer realistic and instead cover even the unrealistic and unlikely to reduce liablity.
This unfortunately can also have the opposite result in causing people to not know which warnings to heed and which are simply lawyer speak to reduce liability if something did go wrong. Which in turn has made many product instructions and labels worthless.


It should never be an issue.
Even the slightly different potential pressures are minimal when considering thier percentage difference of the overall pressure, and compare it to the proof loads both are expected to safely fire.
The primary potential issue is the lead. If you put a really heavy long 5.56 in a .223 and the bullet is or is nearly touching the rifling prior to being fired it will be operating beyond intended pressure. You could potentially have an issue with a 70+ grain round in a .223 jammed against the rifling.
That same rifle though will likely have a twist rate that cannot stablize such a heavy bullet anyways, and so choosing that ammunition would result in poor results.
Many companies also give a lead closer to 5.56 even in thier .223 labeled rifles. This may be for compatibility or to reduce liability. The downside is it can reduce accuracy with lighter weight bullets, reducing performance for those getting a .223 for actual varmint hunting. The longer jump to the rifling results in less predictable results, and an inch difference between shots when hunting a rodent could be significant.

or .308 vs 7.62 for that matter

.308 and 7.62 are the reverse, with the civilian round being the higher pressure one.

 

[alsaqr]

As far as I know, they do label all the boxes 5.56.

Few weeks ago i was present on a firing range when soldier showed me some ammo he had bought. The box was labeled .223 but the ammo inside was military 5.56mm.

 

[ny32182]

With the gazillion 5.56 guns, gazillion .223 guns, and billions of rounds of each kind of ammo out there, if swapping them were really dangerous, you'd read about 100 kb'd guns every day on the internet.

I don't recall ever reading about a KB'd .223 where the root cause was in-spec 5.56 ammo.

The warnings are thrown in there for stacking of extremely rare edge cases of the wrong ammo with the wrong chamber, but realistically it is not a problem, or you'd hear about it all the time.

I'd guess that 99.9% of everyone who owns a 223/5.56 gun and doesn't spend every waking minute on the internet is wholly unaware that there is any difference.

 

[cfullgraf]

Why would any one have different names and specs for nearly the same cartrage? If 5.56 was the first made why not have them all 5.56 mm.

The practice of different names for the same cartridge is rampant on both sides of the Atlantic.

The easiest, generally, the Europeans use the form "XX x YY" where XX and YY are some measurement in millimeters. The first number is the caliber and the second is the length of the case. Example would be 9 x 19 (9 Luger) or 5.56 x 45 (223 Remington) or 7.62 x 51 (308 Winchester).

Add an "R" to the nomenclature and it indicates a rimmed cartridge.

Then, the manufacturers name things differently. For a while, Colt chamber revolvers in 38 Special but called the round 38 Colt (or maybe 38 long Colt) in an effort to sell their own ammunition.

Then you have Remington making the 6mm Remington and renaming it the 244 Remington, then naming it back (or maybe it was the other way around). Same cartridge, different names in an effort to boost sales.

380 ACP is also called 9mm Corto, 9mm Short, 9x17, and maybe a few others tossed in.

And what about 38 ACP and 38 Super. Exact same round dimensionally but do not fire a 38 Super in a 38 ACP firearm if you value your fingers.

And this just scratches the surface.

You must be tearing your hair out by now.

 

[Al Thompson]

I don't recall ever reading about a KB'd .223 where the root cause was in-spec 5.56 ammo.

Not a Ka Boom, but popped primers tying up the rifle are very commonly due to 5.56 in .223 chambers. This is pretty heavily documented, especially amongst high volume AR trainers.

Not trying to "one up" the replies, but I think this was asked and answered. Check out the link posted by BradN and alsaqr.