.223 vs 5.56

Discussion in 'General Firearms & Ammo' started by wegriffin8642, Aug 25, 2009.

  1. wegriffin8642

    wegriffin8642 New Member

    Jun 24, 2009
    Does any one on this forum shoot NATO 5.56 55gr rounds in their .223? I have a Ruger Model M77 and would like to shoot the 5.56 rounds in the rifle but am concerned with safety (?) issues. Any comments/recommendations would be appreciated.

  2. crazy_taco

    crazy_taco New Member

    Aug 18, 2009
    El Paso
    I would consult Ruger on that one. Which Nato round are you planning to be firing?
  3. navyguy

    navyguy TGT Addict

    Oct 22, 2008
    DFW Keller
    I'm not a expert in this area, but I've been told you can safely shoot .223 in 5.56, but not the other way around unless you've got one of the hybrid barrels like DPMS (Wilde). But as suggested, be guided by what the manufacturer says.
  4. GI-John

    GI-John Hurry up and wait!! TGT Supporter

    Apr 26, 2009
    Houston/San Antonio TX
    Consult manufacturer...

    You can fire .223 from a gun chambered for 5.56. It is possible to fire 5.56 in a .223 chambered gun but not reccomended. See 5.56 is loaded to higher pressures and most if not all .223 chambered guns are not designed to take those pressures. People do it with their mini-14's but I wouldn't do it personally.

    With out getting to technical, The 5.56 has a thicker brass casing to handle the higher pressure. The 223. is not to this standard, most warnings will say that chambering a 5.56 in a 223. chambered rifle "Could result in firearm damage and bodily injury." Better to play it safe
  5. Texas1911

    Texas1911 TGT Addict

    May 29, 2017
    Austin, TX
    NATO ammo can be loaded hotter, and the walls are thicker in the brass. This is accounted for in the NATO chamber, which is cut with a more open profile than the .223 Rem.

    I personally would leave the military ammo to the NATO chambered guns.
  6. wegriffin8642

    wegriffin8642 New Member

    Jun 24, 2009
    Thanks for the responses. I've seen only one cracked chamber (not a .223) and it looked nasty as did the guy's forearm...I'll heed your advice.
  7. Texas1911

    Texas1911 TGT Addict

    May 29, 2017
    Austin, TX
    It's like driving without a seatbelt. 99% of the time, there's nothing that comes of it, but that 1% you sure do pay for it.
  8. Texas42

    Texas42 TGT Addict

    Nov 21, 2008
    Just as an aside, I think the 5.56 is a hair shorter, and the chamber has more tolerance generally (made to be reliable more than moa accurate). This causes .223's in a 5.56 chamber to suffer a little in accuracy, though some chambers, like the RRA one, are designed to shoot both.

    These are things I have read. I don't know from personal experience.
  9. Bullseye Shooter

    Bullseye Shooter Active Member

    Apr 28, 2008
    Texas Panhandle
    This is from the Winchester website and pretty much sums it up:

    There are a lot of questions about these two cartridges. Many people think they are identical - merely different designations for commercial and military. The truth is that, although somewhat similar, they are not the same and you should know the differences before buying either cartridge.

    The cartridge casings for both calibers have basically the same length and exterior dimensions.
    • The 5.56 round, loaded to Military Specification, typically has higher velocity and chamber pressure than the .223 Rem.
    • The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.
    • The 5.56mm and .223 Rem chambers are nearly identical. The difference is in the "Leade". Leade is defined as the portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. It is also more commonly known as the throat. Leade in a .223 Rem chamber is usually .085". In a 5.56mm chamber the leade is typically .162", or almost twice as much as in the 223 Rem chamber.
    • You can fire .223 Rem cartridges in 5.56mm chambers with this longer leade, but you will generally have a slight loss in accuracy and velocity over firing the .223 round in the chamber with the shorter leade it was designed for.
    • Problems may occur when firing the higher-pressure 5.56mm cartridge in a .223 chamber with its much shorter leade. It is generally known that shortening the leade can dramatically increase chamber pressure. In some cases, this higher pressure could result in primer pocket gas leaks, blown cartridge case heads and gun functioning issues.
    • The 5.56mm military cartridge fired in a .223 Rem chamber is considered by SAAMI (Small Arm and Ammunition Manufacturers Institute) to be an unsafe ammunition combination.
  10. thorkyl

    thorkyl Active Member

    Oct 13, 2008
    Brazoria County
    I have both 5.56 and 7.62 NATO arms

    so my rule is...

    223 in 556 ok 556 in 223 not ok
    7.62 NATO in 308 ok 308 in 7.62 NATO not ok

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