5.56/.223 - I just dont get it

This is a discussion on 5.56/.223 - I just dont get it within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; As some of you know, I just purchased my first AR-15 lower and am building u p my first AR rifle. Since I will need ...

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Thread: 5.56/.223 - I just dont get it

  1. #1
    Distinguished Member Array Tally XD's Avatar
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    5.56/.223 - I just dont get it

    As some of you know, I just purchased my first AR-15 lower and am building u p my first AR rifle.

    Since I will need ammo to use with it, I have been reading everything I can find about ammo for the 5.56/.223 rifles.

    Just too much to digest

    Anyway, can anyone explain to me why there is a 5.56 chamber when, from what I gather, there is physically NO DIFFERENCE between it and .223???

    Why sell a 5.56 chamber barrel if its the exact same as .223?

    I do understand that military grade 5.56 is loaded to a much higher pressure than commercial .223, so it makes sense to have a receiver built to withstand the higher pressure.

    So, you say 5.56 is simply the NATO metric equivelant to .223? Is it that simple?

    That leads me to other questions. If my AR is built to 5.56 specs, should I try to find 5.56 ammo to use in it or just buy the best .223 ammo for my purposes? I am just not finding any ammo that is specifically listed at 5.56mm

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  3. #2
    Senior Member Array Pete Zaria's Avatar
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    OK, I don't have a 5.56/.223 rifle (so please correct me if I'm wrong) but from what I understand:

    .223 WILL fit in a 5.56mm chamber.
    5.56mm may or may not fit in a .223 chamber but is not recommended for use.

    .223 may have a very very slight accuracy edge, but 5.56mm chambers are preferred for their versatility, since you can safely fire either ammo.

    The differences are in shoulder angle and case length.

    Some relevant links:

    The Gun Zone -- SAAMI on 5.56 v. .223 Remington

    Fulton Armory: 5.56 Ammo in .223 Chamber

    Peace,
    Pete Zaria.

    Edit: Wow, I just noticed that one of my links was to a "white pride" site, and we sure don't want that around here, so I'll copy and paste the relevant post here and remove the link:

    "I know I've mentioned this a time or two in other threads, but I wanted to bring it up again after a conversation with an acquaintance of mine over the weekend.

    Contrary to popular belief, 5.56mm is NOT another name for the .223 round, as opposed to 7.62x51 being the same as .308 NATO. The 5.56 round was designed after the common sporting round, but has two slight, although important, differences. Both are minor, but enough to cause some major if not deadly problems if you put 5.56 into a .223 chamber. .223 may be fired in a 5.56 chamber however. Here are the reasons why:

    1) The 5.56 round has a length .002 longer than the .223 round.
    2) The 5.56 round has a slightly steeper shoulder angle.

    What this all boils down to, is that unless your .223 is specifically chambered in 5.56 to accomadate the military ammunition, you run the risk of blowing the gun up in your face. Colt and Bushmaster chamber ALL their .223 in 5.56. A few other companies chamber their AR15s in 5.56 as well. The big danger is in using 5.56 in bolt action rifles or the Ruger Mini 14, OR AR15s manufactured by some of the lesser known companies, particularly those that are not mil-spec or defense contractors.

    While a great majority of dealers and even gunsmiths will assure you they are the same round, they are not! This is exactly why certain firearms manuals SPECIFY NOT to use military ammunition in their rifles! They know! The combination of a slightly longer casing and steeper angle on the shoulder of the 5.56 round, can cause the bolt to not completely close and lock. It's the equivalant of placing a .22LR into a .22L.

    Many people purchase 5.56 because it is cheaper than .223, but unless your gun is chambered for that specific round, please do not use it! It's not worth the possibilty of the bolt not closing completely before the rifle fires. If that happens, you will lose an eye, a hand, or even your life. Play it safe! Only fire what your manual recommends."
    - Doug @ stormfront.org
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    Ok, .223 is basically the commercial equivalent to 5.56x45 NATO ammo, the dimensions of the ammo are the same. However the NATO round has a higher pressure, which makes it generally unsafe for use in .223 chambered rifles.

    As far as ammo, mil spec stuff like Lake City Surplus will be 5.56 loads, stuff at Wally World is generally .223, I just buy whichever one is cheaper for the stockpile.
    gottabkiddin likes this.
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  5. #4
    Senior Member Array Pete Zaria's Avatar
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    Quote Originally Posted by buckeyeLCPL View Post
    Ok, .223 is basically the commercial equivalent to 5.56x45 NATO ammo, the dimensions of the ammo are the same. However the NATO round has a higher pressure, which makes it generally unsafe for use in .223 chambered rifles.

    As far as ammo, mil spec stuff like Lake City Surplus will be 5.56 loads, stuff at Wally World is generally .223, I just buy whichever one is cheaper for the stockpile.
    Unless your rifle is chambered for 5.56mm, from what I understand, what you're talking about doing is a very dangerous practice. Click the second link I posted above.

    Peace,
    Pete Zaria.
    Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has.
    - Margaret Mead


    "Booger Hook Off the Bang Switch" - unknown

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    Pete, I said it's unsafe to fire 5.56 ammo out of .223 chambered rifles.

    My work rifle and home AR are both 5.56, with a mini-14 in .223, I make sure the Mini doesn't eat any of the 5.56 ammo that I have.

    Unless you want a strictly competition rifle, I would go with the 5.56 chamber.
    Fortes Fortuna Juvat

    Former, USMC 0311, OIF/OEF vet
    NRA Pistol/Rifle/Shotgun/Reloading Instructor, RSO, Ohio CHL Instructor

  7. #6
    Senior Member Array Pete Zaria's Avatar
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    Oops - missed that part. You got it spot-on. "My bad" as they say.

    I agree, a battle rifle is much more versatile in 5.56.

    Peace,
    Pete Zaria.
    Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has.
    - Margaret Mead


    "Booger Hook Off the Bang Switch" - unknown

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    VIP Member Array AZ Husker's Avatar
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    Quote Originally Posted by Pete Zaria View Post
    Colt and Bushmaster chamber ALL their .223 in 5.56. - Doug @ stormfront.org
    My Colt Match Target M4 Carbine is clearly marked "Cal. 223". Are you saying it's OK in THIS gun to use 5.56?
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    Senior Member Array Pete Zaria's Avatar
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    Quote Originally Posted by AZ Husker View Post
    My Colt Match Target M4 Carbine is clearly marked "Cal. 223". Are you saying it's OK in THIS gun to use 5.56?
    Obviously not.
    That part of Doug's post was contradictory - I was only reposting what I found on another forum via Google. It seemed like a good post to me, but I didn't catch that error. Also note his "refer to the manual" note, which I'm sure would clarify that you should only run .223 in that gun.

    I said right upfront I'm no .223/5.56 expert and to correct me if I was wrong.

    Peace,
    Pete Zaria.
    Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has.
    - Margaret Mead


    "Booger Hook Off the Bang Switch" - unknown

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    AH
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    Not to hijack the post but is there somewhere i can compare or see the difference between the Nato 5.whatever and the civilian 223/308 and so on?

  11. #10
    Ex Member Array Ram Rod's Avatar
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    Military ammo or the designations should never be used in civilian chambered rifles. The difference is in the lead (head-spacing) and pressures. 5.56/.223 and 7.62(x51)/.308.
    Winchester Law Enforcement
    7.62x51mm NATO or 308 Winchester? What's the Difference?
    Can I use 308 for 7.62X51 ? [Archive] - THR
    Be safe.

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    Member Array echo5tango's Avatar
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    here's the important part:
    The .223 Remington and the 5.56mm NATO, when checked with a chamber ream from a reliable manufacturer of each, also have discernable differences in the areas of freebore diameter, freebore length (leade) and angle of the throat.
    IMO, the key difference is the throat

  13. #12
    Member Array JoshL's Avatar
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    Everything you want to know about 5.56/.223:

    Ammo Oracle

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    VIP Member Array aus71383's Avatar
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    You can read about this on Wikipedia and it is the correct answer. Try looking it up there. I can sum it up:

    Chamber pressure in .223 Remington is measured to standard commercial specs at the base of the case. Chamber pressure in 5.56x45mm NATO is measured at the case mouth, and is a significantly higher number, but is hard to compare since the pressures are measured in different places. The internal dimensions of the chambers are different. The .223 is much tighter that the 5.56 - also you can tell 5.56 ammo is loaded to higher pressures because it has more velocity with the same bullets. So, its safe to shoot .223 out of 5.56, but not safe to shoot 5.56 out of anything marked .223.....or even some things marked 5.56 because some companies have been putting out barrels marked 5.56 that don't have the correct chamber dimensions. Hope this helps...

    Austin

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    Member Array PeaceKeepr's Avatar
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    So, just get a 5.56 barrel and you're good to go?
    If guns are outlawed, only outlaws would have guns.

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    My Rock River can use .223 or 5.56. It's called a Wylde chamber or something like that. NATO chamber and Wylde chamber? - Yahoo! Answers

    It says 5.56 on it though, as do my mags.
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