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5.56 vs .223 question

Discussion in 'Rifle Discussion' started by atypicalparkie, Dec 14, 2010.

  1. atypicalparkie

    atypicalparkie sowfeast poetland, ohraygun Member

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    So, is my understanding correct: you can fire .223 cartridges in a firearm chambered for 5.56 milspec, but never the other way around?
    Just curiosity and wanting to add to my own education (plus not wanting to do anything idiotic down the road :thumbup:)
     
  2. madcratebuilder

    madcratebuilder Ardenwald, OR Well-Known Member

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    Some 5.56 nato spec may have a longer OAL and when used in a .223 chamber the bullet well be pushed tight against the lands (leade) This may cause an overpressure situation.
     
  3. atypicalparkie

    atypicalparkie sowfeast poetland, ohraygun Member

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    Cool, man. That's what I had read but didn't really get it. But, you could do the other way round, i.e. fire .223 from a 5.56 rifle, yeah? Or would the round be just a hair undersized to operate correctly?
     
  4. spengo

    spengo GLORIOUS CASCADIA Active Member

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    In general, yes. There is one exception though. The Ruger Mini-14 is always marked .223 but it can fire 5.56 safely.
     
  5. Bhowe

    Bhowe Seattle Member

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    My experience is that they are mostly interchangeable. Where you have a gas system operating the action, there is a way for the extra pressure to escape without causing damage. If you have a .223 labeled bolt gun, I would probably stay away from the 5.56. Most AR's and such you will not have a problem either way.
     
  6. spengo

    spengo GLORIOUS CASCADIA Active Member

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    I dunno, there are some .223-chambered varminting ARs with tight match chambers that may be bad to try and put 5.56 in. Most people don't have those though.
     
  7. Bhowe

    Bhowe Seattle Member

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    No you are right, I left that part out I guess. I do have a custom made match grade Douglas Barrel for an SPR type rifle on an AR and I had the chamber made for match tolerances in .223. It would not be reccomended to shove a 5.56 in there. It really doesn't even like cheap .223! Also I have shot indoors with silencers on an M4, .223 is pretty quiet, the 5.56 didn't even sound suppressed. This tells me that there is a significant difference in pressures between .223 and the LC 5.56 XM193.
     
  8. dario541

    dario541 medford, or 97504 Member

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    The manual for the Ruger Mini-14 says that its caliber is .223 (5.56mm). But their target guns are made only for the .223. The safest thing to do is always check your owner's manual.
     
  9. nixuser

    nixuser nw Member

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    i think this sum's it up :)

    .223 Remington vs. 5.56x45 - Gun & Game Forums

    .223 Remington vs. 5.56x45
    This subject comes up from time to time. I ran across this article on 6mmbr.com. Covers it very well.



    .223 Remington vs. 5.56x45--Chambering and Throat Considerations
    Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.
    Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington? The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "Chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber. SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer."

    :)

    __________________
     
  10. Gunner3456

    Gunner3456 Salem Well-Known Member

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    That's right. There is a significant difference between 5.56 and .223 both in pressure and in bullet speed - the 5.56 being the more powerful.
     
  11. atypicalparkie

    atypicalparkie sowfeast poetland, ohraygun Member

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    maaaaaaaan I LOVE this board:banana:!
    That's great info. And cool to know that specifically about the Mini-14, a buddy here on the board has one, the 1st one I've ever shot & me likey! Even though we were in snow & it was getting dark, it was great. We were shooting .223 only, and that was before the 5.56 vs .223 question was even on my radar. Until he was explaining the similarities/differences to me... but I'm still at the stage of caliber-info overload and tend to remember things all bass-ackwards!

    Seems like a Mini-14 that was specifically rated to handle 5.56 pressure and .223 both would be pretty dang handy for ammo availability etc.



     
  12. Gunner3456

    Gunner3456 Salem Well-Known Member

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    Two things. First, the "target" model of the mini-14 isn't rated for 5.56 but all the rest are.

    Second, you will change your point of aim switching back and forth. At least I find that to be true, especially bad at longer ranges since the 5.56 flies much faster and flatter.

    Cliff
     
  13. i8asquirrel

    i8asquirrel Keizer, oregon Member

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    The simple answer is to take any rifle in ? to a qaulified Gunsmith and have the check/ cut the throat with the desired amount of freebore....:thumbup:
     
  14. atypicalparkie

    atypicalparkie sowfeast poetland, ohraygun Member

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    Ah, Cliff that's good to know. Since I've so far only owned handguns, I sure am glad to get info from all y'all who know these things. So much I need to learn!!
    And i8asquirrel, good advice. I finally am starting to understand a little more about what's what.

    Though the POA would be different with either type, it does seem that being able to shoot both .223 and 5.56 would be handy, as long as I'd eventually get used to the differences in behaviour. It'd be fun learning, that's for sure.
     
  15. newt

    newt Corvallis Member

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    You really should not put NATO spec 5.56 rounds in a .223 chamber. More because of pressure than dimensions. NATO weapons test pressure at case mouth, different than SAAMI. This exacerbates the pressure difference and basically will equal a 20,000 psi difference. You can get operating problems with brass, extraction problems, screwed up primers and occasionally catastrophic failure.

    Occasionally, some chambers are marked .223 REM that are actually 5.56, but I wouldn't rely on that.
     
  16. deen_ad

    deen_ad Vancouver, WA Well-Known Member

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    The new target models are .223 ONLY. The rest of the line is still .223/5.56 (unless you have one of the rare .222's!!)

    ----------------------------------------------------------

    The "Trade Rating" is low by 3
    Not everyone posts it I guess.

    Deen
    NRA Benefactor/Recruiter
    WAC member
    SWWAC member
     
  17. madcratebuilder

    madcratebuilder Ardenwald, OR Well-Known Member

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    The 20,000 pressure difference has been debunked. NATO and SAAMI use different sensors to measure pressures. CIP using the same type sensors defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56 mm NATO.
     
  18. i8asquirrel

    i8asquirrel Keizer, oregon Member

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    In my personal firearms I have no issue swapping them back and forth with no problems for years.....:D


    But I do the same with 7.62x51 and .308 winchester.

    .300whisper and 300 aac black out

    **** maybe I should start buying lottery tickets after all!

    Good luck
     
  19. BroncoFan

    BroncoFan Eastern Oregon Well-Known Member

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    Do you have a citation for this? I'm not impuning your information but would like to see this for myself. I've looked around and can't see the issue where it's been settled. Bi_mart was having a sale for $5.99/box for 5.56 while the .223 was still $9.99.

    I'm wondering if this issue is the same for .308 vs. 7.62 NATO?
     
  20. Ned Christiansen

    Ned Christiansen MI New Member

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    This is from a contact at ATK / Federal Cartridge. Italics are mine:

    0000000000000000000000000000000000000000000000000000

    5.56 vs/ .223
    To ensure operational reliability, the 5.56 round is designed to operate at significantly higher pressures, namely just short of 59,000 psi (case mouth meaured) which equates to almost 62,000psi when measured via conformal transducer (as done by SAAMI).

    The SAAMI max set forth for the 223 is 55,000psi (conformal transducer).

    To facilitate operating under these higher pressures, a 5.56 cartridge case possesses a stronger web design (thicker case walls towards the head), reducing internal powder volume, an important consideration for reloaders.
    The remaining differences are found in the chambering of the weapon. A 5.56 chambered weapon differs from a .223 in the throat and freebore. A 5.56 throat is approx. 30 thousandths of an inch longer and 3 thousandths of an inch larger in diameter than a 223 chamber. In addition, the throat or “start point” of the rifling, the taper with which the lands begin, is at a lesser angle, more gradual in a 5.56 than in the .223.

    These rather small, but very important differences, allow peak pressures to drop adequately before the bullet engages the rifling and also allow for more build-up of fouling and shooting residue without impeding function.

    What does all this mean? In short, you can safely fire all 5.56 AND .223 ammunition in a gun properly chambered for 5.56. You MUST NOT fire 5.56 ammunition in a 223 rifle. As case in point, I fired XM193 5.56 ammunition in a .223 test barrel with average pressures (conformal transducer) of 72,550 psi, and peak pressure registered at 76,250 psi. Continued shooting of 5.56 ammunition in guns not chambered for 5.56 will show many warning signs of over-pressure, such as flattening of primers, smearing of the head stamp, dropped primers, blown primers and pre-mature wear on extractors and bolts.
    00000000000000000000000000000000000000000000000000000000