Can i shoot 556 NATO out of my AR-15

SAAMI .223 max. pressure is less than that specified for 5.56 NATO. It is also measured at a different place on the cartridge. This makes it difficult to make a direct comparison.

NATO 5.56 maximum pressure for 5.56 and CIP maximum pressure for the .223 are the same. This suggests that maximum pressure specifications alone are not particularly relevant for comparing .223 and 5.56. Portuguese ball was mentionned. If it is manufactured according to NATO spec, its maximum pressure would be no greater than that of current European CIP sporting .223 ammunition.
The bullet configuration of current NATO ball may differ from .223 ammunition. The NATO chamber has different dimensions for this reason. It is POSSIBLE that a NATO round MIGHT be an interference fit in the throat area of a SAAMI chamber. This COULD increase pressure. And this is where the concern lies with the use of 5.56 in a SAAMI chamber. The concern is because of the mechanical fit of the NATO round in a SAAMI chamber.

Further, while there are theoretical maximum pressure levels specified, these may not be the same as the mean pressures actually developed by a given lot of ammunition. Do factories actually load cartridges at the absolute maximum pressure permitted by the standards organization?
 
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Better question to the 5.56 vs 223 or 7.62 vs 308 would be can you safely shoot 30-06 in a rifle chambered for 30-06? We all know that the 30-06 was a military round and many civilian rilfes are chambered for it.










Just kidding. I wanted to stir the pot a little.
 
Bcviking said:
I bought a bunch of Portuguese 556 NATO surplus and i have a AR the upper has no caliber markings on it i heard if its chambered in 223 only i could hurt my gun? i bought the gun used the only markings is a keyhole mark on the upper no markings on the barrel and the lower is a CMMG any thoughts??
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There's gotta be some marking on the barrel somewhere. Did you take the handguards off? It might be under there.

I know my Colt AR-15 has the 5.56 1/7 twist rate marked right on top of the barrel in front of the front sight.

BTW, where did you get the surplus ammo, and for how much??
 
acrashb how many rounds of 556 and 223 have you shot? myself maybe 100,000 in all diffrent types of rifles. i do it for a living. instead of being an arm chair expert try doing it yourself. its the same round, if the head space on the rifle is fine shoot the thing. you must be one of those guys who only buy ammo at canadian tire? the guys in afganistan, the guys i support shoot all diffrent types of 556/223 its the same made all to the the rough same standard. yes some does chamber better than others but its the same your ignorance is truly blinding. next you will tell me that 30-06 isint 30-06 or that 7.62 and 308 is diffrent. i do this for a living what do you do?
 
angrysoldier said:
its the same round,
[...]
the guys in afganistan, the guys i support shoot all diffrent types of 556/223 its the same made all to the the rough same standard
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Hmmm....

1) You're factually, demonstrably and serially wrong on this. You might as well shout that the sky is green - it isn't. You could just read what I've provided and graciously say "hey, I was wrong". Have you read any of the links? If so, what are your thoughts on the information provided?

Some more food for thought: some AR's designed for 5.56 will not run reliably on .223, because the gas ports are too small - they are designed for the higher pressure of the 5.56.

2) Yippee.

First, 223 in a 5.56 chamber is just fine, proving nothing. The guys you support are all using firearms with 5.56 chambers.

Second, I'd be very surprised to find Canadian or other allied armed forces using commercial .223 - in fact, I'd like you to prove that they do so as a matter of policy. What is the NSN or Canadian equivalent for, say, Winchester 62gr FMJBT?

Third, it is absolutely not "made all to the rough same standard" (as discussed in 1 above)- you're very wrong on this. SAAMI (not CIP, since we're in North America) and NATO use different standards, and they aren't "rough".

For example, NATO specifies outcomes (e.g., velocity) - if they were "rough", BDC's wouldn't work.

Also, pressures are different (to be fair, the standards use different measuring techniques, but the pressures are still different), as you would know if you had taken a moment to increase your knowledge by checking the links I have provided.
 
i bought 1000 rounds of Portuguese 556 NATO steel core for $350 at a surplus store in Vancouver i bought all that he had he says he will never get any more in :<
 
Bcviking said:
I bought a bunch of Portuguese 556 NATO surplus and i have a AR the upper has no caliber markings on it i heard if its chambered in 223 only i could hurt my gun? i bought the gun used the only markings is a keyhole mark on the upper no markings on the barrel and the lower is a CMMG any thoughts??
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If you take the hand guards off you should find a stamping on the barrel showing both the calibre and barrel twist rate.
 
tiriaq said:
It is POSSIBLE that a NATO round MIGHT be an interference fit in the throat area of a SAAMI chamber. This COULD increase pressure. And this is where the concern lies with the use of 5.56 in a SAAMI chamber.
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All the 5.56 I've seen has been no more than 1.750" - cut per .223.


Ar180shooter said:
Yes, NATO pressures are higher than saami specs, and as mentioned in the .223 vs. 5.56 sticky
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All hail the sticky!!!

Ar180shooter said:
the external case dimensions of 5.56 vs. .223 are essentially identical
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Um, No. they are nuts on identical

Ar180shooter said:
Because of this, I would not advise shooting military 5.56 rounds in a .223 spec chamber!
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So say stickys everywhere!


Ar180shooter said:
The 5.56 NATO has thicker case walls
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Says who? The sticky? You? have you ever measured case wall thickness?

It would be refreshing if people stuck to posting what they know from personal experience as opposed to regurgetating what they read elsewhere.
I suppose post counts would likely suffer.
 
beltfed said:
All hail the sticky!!!
[...]
Says who? The sticky? You? have you ever measured case wall thickness?
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The sticky: http://www.canadiangunnutz.com/forum/showthread.php?t=418462 - not that anyone who needs to do so actually reads it...

Regarding case capacity, I've measured the water grain capacity of many 223 and 5.56 manufacturers. While I don't think there is a cut-and-dried answer (for example, Lapua made a change a few years ago that added a grain or so, taking current cases, sized and trimmed, to 31.2 grains of water in my measurements - before that they measured more like 5.56 cases), the 5.56 cases I measured had, on the whole, noticeably less capacity than the 223 cases. Having said that, I don't have records of the 5.56 cases.
 
beltfed said:
Um, No. they are nuts on identical
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Close, but not "nuts on"... please see the tech detail below. There are some minor differences.

beltfed said:
Says who? The sticky? You? have you ever measured case wall thickness?

It would be refreshing if people stuck to posting what they know from personal experience as opposed to regurgetating what they read elsewhere.
I suppose post counts would likely suffer.
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The 5.56 cartridge does in fact have slightly less case capacity than its .223 SAAMI cousin... according to published sources, about 3/10ths of a grain of H2O less.

The .223 Remington has 1.87 ml (28.8 grains H2O) cartridge case capacity.

800px-.223_Remington.jpg


The 5.56x45mm NATO has 1.85 ml (28.5 grains H2O) cartridge case capacity.

800px-5.56x45mm_NATO.jpg
 
acrashb said:
The sticky: http://www.canadiangunnutz.com/forum/showthread.php?t=418462 - not that anyone who needs to do so actually reads it...

Regarding case capacity, I've measured the water grain capacity of many 223 and 5.56 manufacturers. While I don't think there is a cut-and-dried answer (for example, Lapua made a change a few years ago that added a grain or so, taking current cases, sized and trimmed, to 31.2 grains of water in my measurements - before that they measured more like 5.56 cases), the 5.56 cases I measured had, on the whole, noticeably less capacity than the 223 cases. Having said that, I don't have records of the 5.56 cases.
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Ya I read it and I think this pretty much sums up my views on the issue:
P.O. Box 299 Geneseo Illinois, U.S.A. 61254 Tel 309-944-6939 fax 309-944-6949 info@armalite.com
August 17, 2009 Rev 0

TECHNICAL NOTE 74: 5.56 NATO vs SAAMI .223 Remington vs Wylde
Chambers

BACKGROUND: We are often asked about whether our rifles feature NATO (NorthAtlantic Treaty Organization) or SAAMI (Small Arms and Ammunition Manufacturer’sInstitute), or Wylde chambers and whether it makes any difference.

FACTS:
.223 Remington (SAAMI standard) and 5.56mm (NATO standard) rifle chambers are almost identical. The difference is largely limited to the “freebore”, the cylindrical space in front of the casemouth, and the “lead” or “leade”, the tapered region that eases the bullet into full engagement with the rifling. NATO and SAAMI cartridges can normally
be used interchangeably with no problem.

The SAAMI chamber incorporates less freebore and a tighter leade, which normally provides better bullet-to-chamber fit and, therefore, better accuracy than the NATO chamber. It is wonderfully suited to match bullets.

Millions of rounds of NATO ammunition have been fired safely in Eagle Arms and ArmaLite’s® SAAMI chambers over the past 22 years. Occasionally a non-standard round (of generally imported) ammunition will fit too tightly in the leade, and resistance to early bullet movement can cause elevated chamber pressures. These pressures are revealed by overly flattened primers or by powder stains around the primer that reveal leaking gasses.

The first few rounds of ALL ammunition, from whatever source or lot, should be checked for signs of pressure or any other defect before firing large quantities.

If you have a problem, you can generally bet that the ammunition meets neither SAAMI nor NATO specifications.

ArmaLite® has adopted a practice of using a modified SAAMI chamber (Wylde) in its stainless steel match barrels. This chamber is better for match use than the NATO chamber, but fires the NATO ammunition perfectly. We use the NATO chamber in all moly (phosphated) and chrome-lined barrels.

NOTE: ArmaLite’s® larger AR-10 series rifles are all chambered with 7.62 NATO chambers. .308 Winchester (SAAMI standard) ammunition functions perfectly in the 7.62 NATO chambers.
Copyright 2009 ArmaLite, Inc. THE WIZ
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Real shooters don't bother measuring anything. What do you think the forward assist is for?...i wack the #### out of it with 4 lb hammer until the round gets in the chamber and let her rip. ...i go through lots of ars this way. lol
 
WWIII said:
Ya I read it and I think this pretty much sums up my views on the issue:
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So, what Armalite is saying essentially is it's safe, but we made changes to our chamberings anyway... just beacuse we had nothing else to do one day...!?

I've read this bulletin before and believe that it's a walking contradiction unto itself... made necessary because Armalite, for a very long time, cut .223 chambers in their AR's when they should have been using NATO chamber specs... I know, I have one, and it only sees .223...

The bottom line is this, if you want to be macho and risk your equipment or your safety, go right ahead, but I'm not doing it, and won't shoot with you if you do...

Out.
 
... Of interest to "reloaders" only, the Military stuff, that I've come across, have the primer "Pocket Crimp" that has to be dealt with before re-priming. .... David K
 
kenjuudo said:
Close, but not "nuts on"... please see the tech detail below. There are some minor differences.

800px-.223_Remington.jpg
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800px-5.56x45mm_NATO.jpg
[/QUOTE]

I'm not sure where those originated Dave, but I'd be very sceptical of it's source. I have never seen a .223 or 5.56 with zero radius shoulder...



kenjuudo said:
The 5.56 cartridge does in fact have slightly less case capacity than its .223 SAAMI cousin... according to published sources, about 3/10ths of a grain of H2O less.

The .223 Remington has 1.87 ml (28.8 grains H2O) cartridge case capacity.

The 5.56x45mm NATO has 1.85 ml (28.5 grains H2O) cartridge case capacity.
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Again, I don't think this is a hard and fast rule, or rule of thumb. I can only report what I know. Some do, some don't.
I've seen pressure signs with .223 labeled ammo and none with 5.56 used in the same firearm shot side by each.
 
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