# .223 is not 5.56x54



## Montana Rancher

I have a bit of 5.56 x 54mm Nato penetrator 62gr ammo.

There is a bit of controversy about the difference between .223 Remington and Nato rounds so here is what I know and am ready to be educated from other sources.

My understanding is .223 Remington is loaded to lower pressures than the Nato rounds so you may not be safe firing Guvment rounds through a civilian bolt action rifle.

My other understanding is that in a "black gun" you can fire either .223 Remington or the Nato 5.56x54,

Please let me know if that doesn't compare to your knowledge.


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## inceptor

If the barrel is stamped with 5.56 you can shoot either. If the barrel is stamped .223 you don't shoot 5.56 since it won't stand up to the pressure.


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## Rigged for Quiet

95% there. 5.56 is necked just a short hair different than .223 so they seat differently in the chamber. In the long run, you can shoot .223 in a weapon chambered for 5.56 with no worries, but 5.56 in a weapon chambered for .223 can have negative implications.

As I undertand it, that and the chamber pressure are the two differences.


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## LunaticFringeInc

Its the case specs that differentiate the two and as such the chamber demenions. They are also loaded to different pressure ratings.

The 5.56 NATO chamber is slightly more generous and has a longer throat compared to the commercially loaded 223. The brass on mil-spec cases are generally thicker as well which is why you are recommended to drop your powder charge slightly lower than the minimum listed in a load manual and carefully work your way up when using military brass. The 5.56 is loaded to slightly higher pressures due to the fact that the military often uses full auto weapons, weapons that need to cycle reliably when freshly cleaned or exceptionally dirty and long over due for cleaning and maintenance due to operational commitments. This is why 223 will readily chamber and fire in a 5.56 chambered weapon without any hick-ups.

Now doing the reverse is a bit of a crap shoot. Shooting 5.56 in a 223 chambered weapon will create higher safe working pressures than the weapon may have been designed to take. This usually aint significant but in this sue happy world we live in, you can bet the bank that the manufactures lawyers have this first and fore most in their minds! While the gun wont likely blow up on you, over stressing it with higher than normal pressures can result in metal fatique and ultimately over and extended period of time result in a catastrophic gun failure with enough rounds. Is this likely to happen? Doubtful but that possibility always exist even though gun manufactures try to build a little "fudge factor" into their designs knowing that many in the public will shoot the mil spec ammo in their fire arms despite warnings not to do so in the owners manual. This is why when you do read the owners manual of 223 chambered weapons they often have a disclaimer in there and it often voids the warranty of the gun.

There are some other far more minor issues between the two but those are the cliff note version.


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## Fuzzee

I agree. .223 is not 5.56x54. It's closer to 5.56x45mm, but it's not quite it either. :mrgreen:


Either way. I'll take any someone's looking to give away.


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## 1skrewsloose

Can't recall the site off-hand, but they had warning pertaining to the same thing when buying ammo. If the barrel says 223 and not 5.56 shoot only 223.


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## alterego

Please correct the 54 in the original post, you can do so by using the edit function. It is a great informative discussion, however I am getting hung up on the 54.


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## Go2ndAmend

I have always wondered about the differences so this is a great post. Does anyone have any informed thoughts on firing 5.56 in single shot weapons. I have an over under .223/20 gauge and a single shot H&R .223. Both are very robust rifles but if it is creating too much pressure I don't want that.


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## Nathan Jefferson

while the info above is correct - I've always been told to not worry about the difference in any modern firearm that was built in the last decade or so. Now-a-days even your .223 bolt guns, while stamped .223, will handle the extra pressure from a 5.56. If you are really worried, try it, look for any pressure signs - but if your bolt gun was made in the mid 90's or newer you probably don't have to worry about it.

I've (and many others) been shooting 5.56 through .223 bolt guns for years with no issues...


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## Smitty901

The only difference you need to consider is pressure. The 5.56 case is thicker so the pressure is higher. If a 5.56 is fire in a barrel chambered for the .223 it could stick in the chamber. I am not going to get into the the third option on chamber right now .
.223 will fire in a 5.56 barrel. Most .223 you find is 55gr most 5.56 barrels are 16 inch 1 in 7 twist. The 55gr does not work well in that setup .
Loss of accuracy and as the range increase the bullet will be farther off target and fail to kill. 
The 5.56 62gr is designed for the a6 inch 1 in 7 barrel . That or the 77gr if you can find it.
You are right the .223 is not a 5.56 but if .223 is all I have it will have to do in the AR's
Both guns different story that is where the other chamber option came in.

Here you go all typed up for you
http://weaponsman.com/?p=604


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## Slippy

He who attempts to shoot ammo that does not match what is inscribed on the barrel is a potential Darwin Award recipient.


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## AquaHull

The 1 in 9 twist was developed for the M855/SS109 62 gr bullets, 1 in 7 twist was developed for the M856 64 gr FMJTracer. 1 in 7 shoots both 62 and 64 gr, but can overstabilize the 62 gr M855's.

I get a bigger splash on a wet pack milk jug at 200 yards with the 1 in 9 twist vs the 1 in 7 twist.

69 gr SMK/OTM shoot better at 200 out of the 1 in 7, as do the Barnes 62 gr TTSX which relies on expansion as opposed to yawing.

For inside of 100 yards I believe a 1 in 9 twist is better since the bullet has a better chance of yawing than a 1 in 7 twist.


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## Notsoyoung

I've heard the same discussion over the 7.62 NATO round and the .308. Generally the same answer applies. A 7.62 rifle can fire a .308 round but you shouldn't fire a 7.62 NATO round through a .308. Generally. If the SHTF, ammo is scarce, and if you have a .223 made by a good manufacturer, then you can probably fire 5.56 NATO rounds with little chance of something going wrong. One thing to keep in mind is that not all ammo is created equal. Even in an emergency, I would be very reluctant to fire 5.56 ammo through a .223 if the ammo wasn't manufactured in the U.S. or Western Europe because of the quality control issue. You might find some ammo that was loaded hotter then the specs call for. On the other hand if there is a group of mindless zombies coming at you and your choice is to use some questionable ammo or a rock........


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## AquaHull

I fire hot SS109 reloads through a 223 ATI chamber with no signs of pressure on the cases or primer. ATI states it's safe to do so and that the chamber is marked 223 for export to countries who can't have military weapons.


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## MI.oldguy

inceptor said:


> If the barrel is stamped with 5.56 you can shoot either. If the barrel is stamped .223 you don't shoot 5.56 since it won't stand up to the pressure.


Also, my mini-14 is marked .223 but YOU can and I have shot 5.56x45 in it its an old 1986 vintage with 1:10 twist and loves the 62 grain ss109....any bolt rifle in .223 I understand would be strong enough for 5.56 as long as the leade(start of the rifling)does not interfere or set back the longer bullet.and I have fired 7.62x51 in my .308 savage 110 with no problems.this is a debate that will go on forever.


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## SDF880

I run into the same thing with my M1A. I only shoot 7.62X51 through it and would like to shoot .308 but have been advised by many not to do it.
I also have had many say it's ok to do so. I look on-line and run into the same thing, it's ok, it's not ok, pressure differences. Who is right?
I have a Saiga .308 that fires either round just fine and would like to be able to do that with my M1A but don't want to destroy that beautiful rifle!
Sorry didn't mean to hi-jack the tread just thought others may have the same question with their 7.62 as they do with 5.56.


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## AquaHull

MI.oldguy said:


> Also, my mini-14 is marked .223 but YOU can and I have shot 5.56x45 in it its an old 1986 vintage with 1:10 twist and loves the 62 grain ss109....any bolt rifle in .223 I understand would be strong enough for 5.56 as long as the leade(start of the rifling)does not interfere or set back the longer bullet.and I have fired 7.62x51 in my .308 savage 110 with no problems.this is a debate that will go on forever.


1 in 10 gives a little more wobble to the SS109, and that's a good thing, otherwise it's like getting stabbed with an ice pik.


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## rice paddy daddy

Ruger states that 5.56 NATO is OK to fire in their Mini 14's even though the barrel is marked .223.
Differences in chamber dimensions, differences in chamber pressure have been noted above. 
Firing 5.56 NATO in a .223 Remington chamber will result in a pressure spike of 10,000 psi or more. That's in addition to the 50,000 psi (give or take) of the .223.
Will your .223 rifle suffer catastrophic failure? Probably not. But its service life will be shortened, perhaps considerably.

It is perfectly alright to fire .308 Winchester or 7.62 NATO interchangeably in a Springfield Armory M1A. It is designed to accept both.


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## SDF880

rice paddy daddy said:


> Ruger states that 5.56 NATO is OK to fire in their Mini 14's even though the barrel is marked .223.
> Differences in chamber dimensions, differences in chamber pressure have been noted above.
> Firing 5.56 NATO in a .223 Remington chamber will result in a pressure spike of 10,000 psi or more. That's in addition to the 50,000 psi (give or take) of the .223.
> Will your .223 rifle suffer catastrophic failure? Probably not. But its service life will be shortened, perhaps considerably.
> 
> It is perfectly alright to fire .308 Winchester or 7.62 NATO interchangeably in a Springfield Armory M1A. It is designed to accept both.


Thanks 
Really like my M1A!


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## rice paddy daddy

SDF880 said:


> Thanks
> Really like my M1A!


My Army Basic Training rifle was the M-14. My stateside issue weapon was the M-14. I had long wanted one of my own.
A few years ago I was fortunate enough to finally be able to afford an M1A.
I found a Standard Model made in 1994, made with mostly USGI parts. Except for reciever (of course) and stock (no cut out for a selector switch). But she looks and fires just like the ones issued to me so long ago. When I hold her in my arms once again I am young and invincible. :mrgreen:
Yes, I too really like my M1A.
Funny thing - when I went to The Pearl Of The Orient (sarcasm) I was issued an M-16A1 and today I have absolutely no desire to own an AR.

Let me give you some links
Best M14/M1A forum - M14 Forum - M14 Forum for M14 M1A Rifles
Some members of that site branched off with their own - Team M14 Forum which is good as well
For M14/M1A refrence, the best is - Different

I am on both forums, same screen name. Come on over!


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## Montana Rancher

alterego said:


> Please correct the 54 in the original post, you can do so by using the edit function. It is a great informative discussion, however I am getting hung up on the 54.


American Eagle Tactical xm193 5.56x54 ammo 100 rds [am eagle xm193 5.56x45 100 rds] - $99.00 : Oquirrh Arms, Guns Ammo and More

I believe I am using the correct number, but it is confusing, you can see from this ad they use them both.


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## SDF880

rice paddy daddy said:


> My Army Basic Training rifle was the M-14. My stateside issue weapon was the M-14. I had long wanted one of my own.
> A few years ago I was fortunate enough to finally be able to afford an M1A.
> I found a Standard Model made in 1994, made with mostly USGI parts. Except for reciever (of course) and stock (no cut out for a selector switch). But she looks and fires just like the ones issued to me so long ago. When I hold her in my arms once again I am young and invincible. :mrgreen:
> Yes, I too really like my M1A.
> Funny thing - when I went to The Pearl Of The Orient (sarcasm) I was issued an M-16A1 and today I have absolutely no desire to own an AR.
> 
> Let me give you some links
> Best M14/M1A forum - M14 Forum - M14 Forum for M14 M1A Rifles
> Some members of that site branched off with their own - Team M14 Forum which is good as well
> For M14/M1A refrence, the best is - Different
> 
> I am on both forums, same screen name. Come on over!


Thank you sir very much!


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## Inor

rice paddy daddy said:


> My Army Basic Training rifle was the M-14. My stateside issue weapon was the M-14. I had long wanted one of my own.
> A few years ago I was fortunate enough to finally be able to afford an M1A.
> I found a Standard Model made in 1994, made with mostly USGI parts. Except for reciever (of course) and stock (no cut out for a selector switch). But she looks and fires just like the ones issued to me so long ago. When I hold her in my arms once again I am young and invincible. :mrgreen:
> Yes, I too really like my M1A.
> Funny thing - when I went to The Pearl Of The Orient (sarcasm) I was issued an M-16A1 and today I have absolutely no desire to own an AR.
> 
> Let me give you some links
> Best M14/M1A forum - M14 Forum - M14 Forum for M14 M1A Rifles
> Some members of that site branched off with their own - Team M14 Forum which is good as well
> For M14/M1A refrence, the best is - Different
> 
> I am on both forums, same screen name. Come on over!


Now that Mrs Inor got her Christmas Garand, I think an M1A will be our next major rifle purchase. I have wanted one forever.

In the meantime, I am going to build at least 1 (hopefully 2) AR-15s from 80% lowers, just because I want to see if I can.


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## PaulS

The difference in the pressures of the two rounds is not enough to cause harm to even the cheapest bolt action rifle. The cartridges have exactly the same dimensions and will chamber in the same gun. The 5.56 has slightly higher pressure and if you are firing in a semi-auto the added pressure may be hard on your gun that is stamped 223. In the tests that have been done no AR was injured by running thousands of rounds of 5.56 through a gun stamped 223 but the gas operated rifle that was tested hit hard enough that it was thought that continuing the use of 5.56 in it would eventually cause harm to the action - not the chamber or barrel.


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## Infidel

rice paddy daddy said:


> Ruger states that 5.56 NATO is OK to fire in their Mini 14's even though the barrel is marked .223.
> Differences in chamber dimensions, differences in chamber pressure have been noted above.
> Firing 5.56 NATO in a .223 Remington chamber will result in a pressure spike of 10,000 psi or more. That's in addition to the 50,000 psi (give or take) of the .223.
> Will your .223 rifle suffer catastrophic failure? Probably not. But its service life will be shortened, perhaps considerably.
> 
> It is perfectly alright to fire .308 Winchester or 7.62 NATO interchangeably in a Springfield Armory M1A. It is designed to accept both.


Absolutely correct on the Ruger but with a caveat. 5.56 ammo is not ok in the newer Mini-14 Target version, this rifle is cut with a .223 chamber only and Ruger specifically warns against using 5.56 ammo. I would avoid the use of 5.56 ammo if I owned a Mini-14 Target, it is perfectly acceptable in all other Mini-14s.

I'm with Inor, my next rifle purchase will likely be a Springfield M1A. I've been wanting one for 20 years or so but for one reason or another just have never gotten around to buying one. Usually it's because another deal comes along that I just can't pass up. Unfortunately I'll probably have to wait until I move out of NY to buy that rifle. I think it may be classified as an assault rifle under the unSAFE Act, not sure might have to look into that.

-Infidel


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## AquaHull

PaulS said:


> The difference in the pressures of the two rounds is not enough to cause harm to even the cheapest bolt action rifle. The cartridges have exactly the same dimensions and will chamber in the same gun. The 5.56 has slightly higher pressure and if you are firing in a semi-auto the added pressure may be hard on your gun that is stamped 223. In the tests that have been done no AR was injured by running thousands of rounds of 5.56 through a gun stamped 223 but the gas operated rifle that was tested hit hard enough that it was thought that continuing the use of 5.56 in it would eventually cause harm to the action - not the chamber or barrel.


Then why is my 223 field gauge smaller than my 556 field gauge


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## MI.oldguy

AquaHull said:


> 1 in 10 gives a little more wobble to the SS109, and that's a good thing, otherwise it's like getting stabbed with an ice pik.


Mine stabilize nicely,on paper,in fact its a strange little mini carbine,it only tosses out brass at a 45 to the shooter and drops it in a nice pile about 8 feet away and shoots 1-1/2 minutes even after 6-7 rounds.I have finally bought a b-square mount and a scope, put a buffer in it and a diy strut so when its warmer I will try it out since the missus said no ar this year.dont mean to hijack this thread but I had to tell cause I'm pretty proud of its looks....pics coming soon.


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## Fuzzee

Montana Rancher said:


> American Eagle Tactical xm193 5.56x54 ammo 100 rds [am eagle xm193 5.56x45 100 rds] - $99.00 : Oquirrh Arms, Guns Ammo and More
> 
> I believe I am using the correct number, but it is confusing, you can see from this ad they use them both.


.223/5.56x45

:: Ammo Oracle


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## PaulS

AquaHull said:


> Then why is my 223 field gauge smaller than my 556 field gauge


The military spec allows for more chamber wear. The cartridges are dimensionally the same - the chambers are different because the military allows for contamination in the chambers of military weapons whereas SAAMI does not.

The military ammo does operate at higher pressures in a small chamber and its maximum allowable chamber pressure is higher to provide for the muzzle velocity specified by the military. The SAAMI average maximum pressurefor the 223 is 52000 CUP (copper units of pressure) and the military ammo average maximum is 55000 PSI (pounds per square inch). It is impossible to compare the two numbers because not only are the two ratings not comparable but the pressures are measured in different areas of the gun. The SAAMI pressures are measured at the chamber and the military pressures are measured forward of the chamber on the barrel.

I do have a chart that shows SAAMI pressures in both CUP and PSI for many cartridges and the 223 - 5.56 are listed as the same pressure - The 223 and 5.56 are both listed as 52000 CUP and 55000 PSI which would lead me to think that the pressures are the same except for the differences in the two chambers. A larger chamber will see less pressure than a smaller chamber with the same cartridge/loading. The 5.56 in a 223 chamber might produce higher levels of pressure but certainly not enough higher to exceed the 61000 PSI extreme limit that gun chambers are designed to withstand on a constant basis. With a gas powered gun designed for lower pressures to operate the mechanism the higher pressure could damage that system - which is why target rifles and pistols are not recommended for firing standard hunting ammunition.


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## Smitty901

More than your ever what to know about 223/5.56
But 100% fact
http://weaponsman.com/?p=604


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## AquaHull

Even more here

:: Ammo Oracle


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