.223 or 5.56mm?

Discussion in 'AUG, MSAR' started by UziGeo, Oct 11, 2006.

  1. UziGeo

    UziGeo Guest

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    Just noticed on my Steyr USR, the barrel is stamped .223 rem. I thought these guns were made for .223 or 5.56mm. I couldn't find anything on a seach. Just bought 1000 rounds of Q3131 2005. I hear that this is excellent ammo, [from AR15.com] but is it safe to shoot in this gun? I know that a gun that is stamped .223 shouldn't use 5.56. Am I wrong here?
     
  2. madecov

    madecov Active Member

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    generally, you are correct.
    Pressures are higher in 5.56.

    However many import weapons were stamped with the "commercial" caliber rather than the military "nato" caliber for political reasons. I would contact Steyr and ask.
     

  3. OTTO

    OTTO Guest

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    5.56mm and .223 are the same round your wepon will fire both with no problem.
     
  4. some_finn

    some_finn Guest

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    :roll: No, they are not.

    99.9% of the time 5.56 NATO works perfectly in .223 Remington guns, but there is always the 0.01%

    The 5.56 NATO has higher max pressure, and the chamber dimensions are a bit different. The commercial .223 specification chamber is a bit "tighter" in the throat area and in some rare cases (often non-standard) 5.56 ammo may "stick" in the chamber creating over pressure.

    Most likely the AUG/USR chamber is actually 5.56 NATO spec even if the "civilian" rifle has .223 Remington stamped on it. I wouldn't worry about it.

    A lot of information on the differences can be found using Google, here's one page for example.
     
  5. BulletBait

    BulletBait New Member

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    .223 and 5.56 chambers can be different.

    5.56 ammo has a wider spec on the case size for what is acceptable to help keep the ammo cost down and production flowing.

    The .223 chamber can be made to a tighter spec and so more accurate shooting than the 5.56 which is made to work even when a little dirty at the price of a small amount of MOA.
    The chamber on many .223 bolt action guns is tighter and so some 5.56 ammo may be difficult to close the bolt on.

    That said, all the major gun Mfs' use the 5.56 chamber on their semi autos, even Ruger.
    Who has always labled their Mini-14 .223, except on some MIL/Police models.
    Guns that don't use the 5.56 chamber are specificly listed as having a target or match chamber, except Colt.
    Colt calls it's nuetered AR15 a "Target Match" even though all they did was cut off the flash suppressor and bayonett lug. The chamber is still the looser 5.56 one.
    Clear as mud?

    Long story short. Your USR uses the 5.56 chamber like 99% of the guns out there, but is labled .223 to help keep the anti-gun types from crying. :roll:
     
  6. OTTO

    OTTO Guest

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    They are close enough that is wont matter i have M-16 gov for the job and it dose shoot both great and a Aug and it shoots the same.

    the web sight even says 5.56 (.223rem) in the tech data.

    http://www.steyr-mannlicher.com/index.php?id=654

    it wont matter at all!
     
  7. UziGeo

    UziGeo Guest

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    There seems to be some discussion whether the USR can use military [NATO] ammunition. I have one, and the barrel is marked . 223 rem. I know that the throat is different between saami chambers and chambers rated for military 5.56 mm ammo. Can you send me the specs on the throat of this barrel? This is what I have found. Thank you so much for your response in advance. George in Florida, USA. I sent this email to steyr, along with a picture of the different chamber specs. I could not post the pic here, no matter how I tried. Here is the hyperlink, if you are interested. http://www.ammo-oracle.com/body.htm#diff I guess it didn't insert a hyperlink. Just copy and paste.
     
  8. STG77

    STG77 Guest

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    The USR barrels were supposedly made by ADI-Lithgow. I'm sure they have 5.56mm chambers.

    FWIW my mid-60s vintage Colt M16 duty rifle is marked ".223" as well, but it obviously has a 5.56mm chamber.
     
  9. UziGeo

    UziGeo Guest

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    Received this email from Austria by way of Steyr USA. Guess this puts this question to rest. Thanks to all....

    The STEYR USR has the same chamber as the AUG. That means you can fire all Military/NATO type ammunition.



    Best regards



    Fritz