.223 v 5.56 question

[Milamber]

I searched and could not find the answer definitively. I know its an old question but my brain is fuzzeled and needs a reboot!

Can I shoot .223 Rem from a AR 15 chambered for 5.56?

Also I saw a guy on here with a birdcage flashhider that was solid at the bottom to prevent dust blow up when shooting prone. Who makes it?

 

[highorder]

Yes, you can shoot .223 in a 5.56 chamber.

Any A2 birdcage lacks a bottom port.

 

[fatcat4620]

Look right here

 

[fanchisimo]

Yes, you can fire .223 from a 5.56 barrel. I can't remember the exact difference but here is a link that outlines it. Granted I'm being lazy but you'll learn more if you read it yourself. Lol.

http://ammo.ar15.com/ammo/project/hist_diff.html

There's a lot of other good stuff if you read it all.

 

[303tom]

YES.............There is no difference between .223 Rem. & 5.56 NATO..............

 

[Sam1911]

YES.............There is no difference between .223 Rem. & 5.56 NATO..............

NO...............That is incorrect!.................

There are chamber differences and ammo specification differences. .223 chambers are generally tighter, and with less head space. 5.56 NATO ammo is loaded to higher pressures and velocity. You can get excessive chamber pressures from firing hot 5.56 mm ammo in a .223 chamber, so it is best to follow the guideline that .223 ammo can be fired in either, but 5.56mm ammo should only be fired in a 5.56mm chamber. (Or one of the alternates like the Wylde chamber.)

 

[Dreamliner787]

Just get AR that's 5.56 and nothing to worry about when plinking with 223s.

 

[Creature]

YES.............There is no difference between .223 Rem. & 5.56 NATO..............

There certainly is a difference.

The .223 Rem cartridge will safely shoot in any rifle chambered for the .223 or 5.56. If you want to shoot 5.56 NATO rounds, make sure you have a rifle designed for the 5.56 military cartridge. Shooting 5.56 in a normal .223 Rem rifle can result in bad things.

The best of both worrlds: 223 Wylde


edit: Sam1911 beat me to it.

 

[helotaxi]

NO...............That is incorrect!.................

There are chamber differences and ammo specification differences. .223 chambers are generally tighter, and with less head space. 5.56 NATO ammo is loaded to higher pressures and velocity. You can get excessive chamber pressures from firing hot 5.56 mm ammo in a .223 chamber, so it is best to follow the guideline that .223 ammo can be fired in either, but 5.56mm ammo should only be fired in a 5.56mm chamber. (Or one of the alternates like the Wylde chamber.)

Just to clarify, the difference is in the freebore and the leade of the chambers. The headspace is the same. It's the 7.62NATO/.308Win that have different tolerances for headspace.

XM193 (55gn FMJ) has a lower pressure spec than XM855 or SS109, the same pressure spec as SAAMI places on the .223 Rem, but remember that spec is derived from a cartridge fired in the 5.56 chamber with the longer freebore and shallower leade. The pressure will be higher if that cartridge is fired in a .223 Rem SAAMI spec chamber. XM855 and SS109 are loaded to a higher pressure AND that pressure is specified when fired from a 5.56 NATO chamber. Firing them in a .223 Rem chamber has been shown to roughly equate to a proof load. Yes, your rifle should handle a proof load, that's the whole point of one after all, but it is only ever meant to handle a single proof in its lifetime. A steady diet of them is not a good thing.

 

[Sam1911]

Yes, a mistake in typing. Headspace and freebore/leade are not the same thing.

The 5.56mm has a longer leade before the rifling begins than .223, which also can increase chamber pressure.

 

[Lovesbeer99]

They are the same. There is a lot of internet speak on this but rarely do you see actual published numbers. When we speak of chamber differences are we speaking of wylde chamber or match chamber or varmint chamber?

There is also a myth that LC brass is thicker in the walls so the pressure is higher but we now know that's not true either.


I could be wrong, and I'll apologize if I am but I'd like to see SAAMI specs for 223 and 5.56 and how they are different from a published source, not a forum typed by a poster. I checked the SAAMI website and they don't list or reference the 5.56.

 

[pcf]

You won't find any SAAMI specs on 5.56x45 NATO because the specifications are covered under STANAG, a NATO standardization.

Directly from SAAMI, page 7, 5.56 Military ammo in a .223 Remington is an unsafe combination.
http://www.saami.org/specifications...1-Unsafe_Arms_and_Ammunition_Combinations.pdf

 

[jmr40]

Technically they are different. But talk about splitting hairs. The factory specs are very, very close for both ammo and chambers. So close that they are both are within acceptable tolerences of each other.

Select ANY chambering and you will find much greater differences. I'll use 30-06 as an example. If you were to randomly select 20 differnt rifles from 5 different manufacturers and carefully measure the chambers you will find just as much difference as if you took 20 different 5.56 rifles and 20 different 223 rifles.

Same with ammo. Measure the chamber pressures on 20 different 30-06 loads from 5 different manufacturers and you will see just as much difference as between 5.56 and 223 ammo.

It is possible to get a certain 5.56 load that is borderline high pressure and fire it in a rifle with a chamber that is cut on the minimum side and get a slightly over pressure situation. But the odds are just as great when buying factroy 30-06 loads and shooting them in various rifles.

Since the military chose to call a 223 a 5.56 and civilians call a 223 a 223 some people seem to think this is significant. I'd be more worried about the various 30-06 loadings and the wide variances of chamber sizes over the years. We could easily have 3-4 different names for various 30-06 loadings, chamber pressures and chamber sizes. But we don't and you rarely hear of any problems. Most folks shoot 223 and 5.56 interchangeably without a clue there is supposed to be a difference. I've yet to hear of a problem.

 

[Sam1911]

So there is is from SAAMI itself: http://www.saami.org/specifications...1-Unsafe_Arms_and_Ammunition_Combinations.pdf

Shall we call that definitive?

CENTERFIRE RIFLE

In Firearms Chambered For ... Do Not Use These Cartridges
223 Remington ... 5.56mm Military

 

[Lovesbeer99]

PCF - thank you so much and I'll now eat my words. That is exactly what I was looking for. Until now I have not seen any legitimate publication that stated the combo was not safe.

Thanks -

 

[helotaxi]

Technically they are different. But talk about splitting hairs. The factory specs are very, very close for both ammo and chambers. So close that they are both are within acceptable tolerences of each other.

In the body of the chamber and in case dimensions, they are actually identical with the exception that one (don't remember which because it really doesn't matter) has tiny radii specified where the body transitions to the shoulder and the shoulder transitions to the neck. Where they are not even close is in the freebore (case mouth to the beginning of the rifling) and leade (angled beginning edge of the lands where the barrel transitions from a smooth bore of nominal diameter to a rifled bore where the lands are a smaller diameter than the grooves). The extra freebore in the 5.56 chamber gives the bullet time to accelerate relatively unimpeded and build up some inertia before being engraved by the rifling. The engraving force is what causes the pressure spike when a round is fired. Additionally, the specified leade angle is shallower in the 5.56 meaning a slightly more gradual build up of engraving pressure.

Select ANY chambering and you will find much greater differences. I'll use 30-06 as an example. If you were to randomly select 20 differnt rifles from 5 different manufacturers and carefully measure the chambers you will find just as much difference as if you took 20 different 5.56 rifles and 20 different 223 rifles.

Same with ammo. Measure the chamber pressures on 20 different 30-06 loads from 5 different manufacturers and you will see just as much difference as between 5.56 and 223 ammo.

It is possible to get a certain 5.56 load that is borderline high pressure and fire it in a rifle with a chamber that is cut on the minimum side and get a slightly over pressure situation. But the odds are just as great when buying factroy 30-06 loads and shooting them in various rifles.

Since the military chose to call a 223 a 5.56 and civilians call a 223 a 223 some people seem to think this is significant. I'd be more worried about the various 30-06 loadings and the wide variances of chamber sizes over the years. We could easily have 3-4 different names for various 30-06 loadings, chamber pressures and chamber sizes. But we don't and you rarely hear of any problems. Most folks shoot 223 and 5.56 interchangeably without a clue there is supposed to be a difference. I've yet to hear of a problem.

The differences are real and clearly documented between the SAAMI .223 cartridge and the NATO 5.56 cartridge and the chambers for each. If you decide to ignore that, so be it, but please don't try to pass your misconceptions off as fact for others. The reason that you haven't heard of a problem (and I've heard of several) is that very few production rifles theoretically chambered in .223 Rem are cut with a SAAMI spec throat. That is specifically to keep people ignorant of the differences (consciously or unconsciously) from blowing themselves up. It's a liability thing at this point simply because some people don't go looking for information and some simply choose to ignore it when it is handed to them.

 

[303tom]

NO...............That is incorrect!.................

There are chamber differences and ammo specification differences. .223 chambers are generally tighter, and with less head space. 5.56 NATO ammo is loaded to higher pressures and velocity. You can get excessive chamber pressures from firing hot 5.56 mm ammo in a .223 chamber, so it is best to follow the guideline that .223 ammo can be fired in either, but 5.56mm ammo should only be fired in a 5.56mm chamber. (Or one of the alternates like the Wylde chamber.)

I can have a buddy that works right here in Lake City call you & tell you that there is not a nickels worth of difference in the .223 & the 5.56 NATO, if you want to give me your phone #.............

 

[Sam1911]

I can have a buddy that works right here in Lake City call you & tell you that there is not a nickels worth of difference in the .223 & the 5.56 NATO, if you want to give me your phone #.............

Tell you what, I'll take what SAAMI says over your buddy's opinion, though I'm sure he's a mighty fine fellow. He may be the janitor, an assembly line worker, an accountant, or the head ballistician, but his word doesn't carry weight if it contradicts SAAMI.


(And if he's the head ballistician, ask him to explain the differences between the two and, IN DETAIL, why he thinks they don't matter. If he can't explain the differences, that should tell you something about your friend. ... If he's the janitor or a line worker ... don't bother.)

 

[X-Rap]

There is much CYA in the answer to your question, I have yet to see a modern production gun damaged by shooting 5.56 in a 223 chamber.
As a reloader I use cases from each and the same data and don't have problems and have shot a mix of factory loaded rounds in both types of guns.
Reloads are a question rarely if never addressed in the argument.
There was a study done by a gun writer that someone here linked to and he did a pretty extensive analysis that showed no Ill effects but still didn't recommend doing it.

 

[Creature]

Don't say you weren't warned.

 

[helotaxi]

There is much CYA in the answer to your question, I have yet to see a modern production gun damaged by shooting 5.56 in a 223 chamber.
As a reloader I use cases from each and the same data and don't have problems and have shot a mix of factory loaded rounds in both types of guns.
Reloads are a question rarely if never addressed in the argument.
There was a study done by a gun writer that someone here linked to and he did a pretty extensive analysis that showed no Ill effects but still didn't recommend doing it.

The cases are identical because the case specifications are identical. You don't see the issue addressed often when reloading because all reloading manuals discuss the reloading for the .223 Remington and their published data is within .223 Remington pressure levels when fired in their .223 Remington SAAMI spec pressure barrel. Only Western Powders (Accurate and Ramshot) publishes data for loads to 62,350psi (5.56 NATO spec). I've seen tests with pressures in the 5.56 PROOF load range when firing 5.56 NATO in a .223 barrel. That's well in excess of a .223 proof load. Modern firearms are, for the most part well over-engineered but that doesn't mean that running them outside their design specs as a matter of routine is a wise practice and will never come back to bite you in the butt.

As far as the difference between LC loaded XM193 and .223 Remington loaded with a 55gn FMJ, there probably isn't a difference other than the crimped primer. XM193 is a US spec load, loaded to a lower pressure and is not 5.56 NATO spec ammo like XM855 or SS109.

 

[pseudonymity]

I've seen tests with pressures in the 5.56 PROOF load range when firing 5.56 NATO in a .223 barrel. That's well in excess of a .223 proof load. Modern firearms are, for the most part well over-engineered but that doesn't mean that running them outside their design specs as a matter of routine is a wise practice and will never come back to bite you in the butt.

Out of curiosity, are those 5.56 rounds at proof pressures jammed hard into the lands? I have wondered just how many generally available commercial loads in 5.56 (or bullets for reloaders) are available that can generate dangerous pressures in a .223 chamber.

Is a hot load in 5.56 going to produce dangerous pressures even if you still have a reasonable jump into the lands? Certainly any 5.56 in a .223 chamber would be ill advised, but I really do wonder about the risks, more out of curiosity than anything else. My only .22 CF is a 5.56 chamber.

 

[Magoo]

Just to throw a monkey wrench at the discussion... Could this OP possibly last past three pages?

I've consistently read over and over about Saiga AK-74s stamped Rem .223. Internet truth holds that the Saiga factory makes no other changes to their manufacturing process than the stamp when "rechambering" one of their rifles from 5.56 to .223.

Granted, that's only one manufacturer and they're working on the safe side of things, certainly not the accuracy side of things.

 

[alsaqr]

There are numerous popular myths concerning 5.56 military ammunition. i know folks whose job it is to accept ammunition for the US Army. This is from the US Army acceptance standard for M193 ball ammunition: MIL-C-9963F:

3.7 Chamber pressure.

3.7.1 Measurement by copper-crush cylinder.-The average chamber pressure
of the sample cartridges, conditioned at 70° ± 2°F, shall not exceed
52,000 pounds per square inch (PSI). The average chamber pressure plus
three standard deviations of chamber pressure shall not exceed 58,000 PSI.

3.7.2 Measurement by piezoelectric transducer.-The average chamber
pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not
exceed 55,000 PSI. The average chamber pressure plus three standard
deviations of chamber pressure shall not exceed 61,000 PSI.

Acceptance standards for M855 ball ammunition. MIL-C-63989C:

3.6 Velocity. The average velocity of the cartridges,
conditioned at 700 + 2° F, shall be 3000 feet per second (fps) plus
or minus 40 fps at ~8 feet from the muzzle of the weapon. The
standard deviation of the velocities shall not exceed 40 fps.

3.7 Chamber pressure. The average chamber pressure of the
sample cartridges, conditioned at 70° + 2° F shall not exceed
55,000 psi. Neither the chamber press~re of an individual sample
test cartridge nor the average chamber pressure plus three standard
deviations of chamber pressure shall exceed 61,000 psi.

What SAAMI does not tell you is the fact that ammunition manufacturers also have acceptance standards.

The only .223/5.56mm ammunition i have known to blow up rifles was .223 caliber made by Winchester.

http://www.thefirearmblog.com/blog/2011/03/04/winchester-5-56-ammunition-recall/

The Winchester recall notice.

http://www.winchester.com/library/news/Pages/News-Product-Warning-and-Recall-Notice.aspx

There is more to the story than simply .223 SAAMI and 5.56mm military chambers. A reputable gunsmith tells me that no company today makes a "SAAMI" chamber. There are at least 12 different .223/5.56mm chambers: Here are some of them. Click on reamer dimensions:

http://ar15barrels.com/tech.shtml

 

[helotaxi]

The "long throat" .223 chambers are very near a 5.56 chamber. While the 5.56 round isn't jammed into the lands of a SAAMI .223 chamber (if it were .223 rounds would jam into the lands as well since the ammo external dimensions are identical) the jump is smaller. That abrupt pressure spike is accounted for with .223 loads while 5.56 loads are built around the more gradual pressure rise from the 5.56 chamber.

As far as availability of NATO ammo and/or bullets, XM855 over-runs, foreign SS109 milsurp and pulled bullets from both are readily available. I've got at least 1k pulled M855 steel core bullets under my loading bench.