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Let me get this straight....*5.56 and .223*

Discussion in 'Rifle Country' started by boredelmo, Feb 24, 2007.

  1. boredelmo

    boredelmo member

    An ar that has a 5.56 barrel WILL fire .223 reliably?

    the mags are all the same?

    does this do any damage? is it bad for the gun?
  2. RecoilRob

    RecoilRob Well-Known Member

    Yes, yes, no and no. Some .223 chambers will get into trouble with 5.56 but not the other way around.

    AR mags won't care which round is in them.

    No damage will be done using SAAMI spec .223 in a 5.56. In fact, most 5.56 is hotter than normal .223 so using the latter should be a tad easier on things.

    Not bad for the gun at all. It won't know that you aren't using 5.56. If it runs on the particular .223 you are using, you are good to go. In larger calibers, the port gas pressures must be kept near GI specs, which means ultra-slow magnum type powders are usually verboten. But, in .223 all acceptable powders will normally make enough gas to run the AR's and shouldn't overstress things.
    Last edited: Feb 24, 2007
  3. dispatch55126

    dispatch55126 Well-Known Member

    A .223 measures at 5.5642
    A 5.56 measues at .2189

    There is some difference BUT the difference is so small that a .223 will swag down to the proper size. The issue become the possibility of increased wear and possible increased stress due to breach pressure and barrel heat. The Mini 30 is the same in that American 7.62x39 measues at .308 and Russian rounds measure at .311. There will be increased wear but depending on the amount of ammo you shoot per day/week/month/year, its not that big an issue. Just make sure and check the manufacturer if there are any warnings or complications.
  4. cheygriz

    cheygriz Well-Known Member

    The Military Spec 5.56X45 chamber has a throat approx .020 longer than a Commercial SAAMI spec .223 Remington chamber. Both use a .224 diameter bullet.
    This "freebore" allows military ammunition to be loaded to slightly higher pressure than commercial .223.

    Roy weatherby pioneered this idea in the 1950s with his Weatherby Magnum line.

    Commercial .223 Remington ammo can be safely used in a Military Spec chamber, but Military Spec. ammo should not be used in commercial .223 Remington chambers.

    Modern rifles have such a large margin of safety built in that it is highly unlikely that high pressure Military ammo would damage a modern .223 commercial gun, but it's still considered a poor practice.
  5. redranger1

    redranger1 Well-Known Member

    So where does this 223 wylde chamber come into play? Will it eat 5.56 ok?
  6. cheygriz

    cheygriz Well-Known Member


    The Wylde chamber, offered by Rock river Arms is a compromise. It is shorter than a MilSpec 5.56, but longer than a SAAMI commercial. It will handle all 5.56X45 and .223 Remington safely.
  7. redranger1

    redranger1 Well-Known Member

    Perfect, thats exactly what i wanted to hear!
  8. Cacique500

    Cacique500 Well-Known Member

  9. Lucky

    Lucky Well-Known Member

    Yea I thouhgt .223 had a bit higher pressures, so .223 always shoots 5.56 but not necessarily the other way around.

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