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5.56 vs .223

Discussion in 'Ammunition & Reloading' started by jvbutter, May 17, 2011.

  1. jvbutter

    jvbutter Cornelius, Or Active Member

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    I have seen some people post 5.56 and .223 as the same ammunition. And I assuemd so. However i have heard that the NATO 5.56 is not the same and more powerful... is this true??? Whats the difference in them?? Will any 223 shoot the 5.56???
     
  2. Billy 4 HP

    Billy 4 HP Skagit Member

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    This should help....

    http://www.armalite.com/images/Tech Notes\Tech Note 45, 5.56 NATO vs SAAMI .pdf

    and some more reasonable info here....

    http://en.wikipedia.org/wiki/5.56x45mm_NATO

    and a bit more here....

    http://ar15barrels.com/data/223vs556.pdf

    And there is a bunch more of both good and bad information available on the net....
     
  3. jvbutter

    jvbutter Cornelius, Or Active Member

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    thx much... clears it up... pretty close to being similar.. newer guns are modified to handle it, but check with manufacture first to ensure. oh and seems the cases on NATO rounds are thicker, less powder. Amongst other differences in size
     
  4. Ben Beckerich

    Ben Beckerich NW Oregon Bronze Supporter Bronze Supporter

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    NATO ammo is loaded about 15,000PSI hotter than SAAMI, when we're talking 5.56 v. .223... you can probably get away with shooting 5.56 ammo in just about any .223, but why put all that extra stress on your chamber? it'll just burn it out that much faster, if nothing else.

    with ARs, it can make an even bigger difference.. but that's a whole topic by itself.
     
  5. deadshot2

    deadshot2 NW Quadrant WA State Well-Known Member

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    One needs to be careful when comparing pressures from published "specs". Pressure measurements can be obtained in a couple of places. One is at the case mouth and another in the "chamber".

    A Nato round developing 3250 fps doesn't generate much greater pressure than a "civilian" round traveling the same speed (bullet weights being equal).
    Basically, the readings are the same, just measured in different places.

    The NATO chamber has a longer leade or greater distance from ogive to rifling on a chambered round. This can alter the pressure readings drastically. Just as any handloader adjusts his powder load depending on OAL, and the resulting jump to the rifling, one needs to expect this if shooting a NATO round in an .223 barrel. It can be particularly dangerous in a tight chambered target rifle with little or no freebore or leade. The additional leade allows for more powder to be employed, yielding higher velocities, with lower chamber pressures but can often result in lower accuracy.