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Using 223 Ammo In A AR-15 Marked 556?

Discussion in 'Black Rifle Forum' started by obiestreasures, Mar 30, 2010.

  1. My question is that a salesman told us that you may have trouble using 223 ammo in a AR-15 that is chambered for 556. I have been reading all I can about the Ar-15's be for I purchase one.My friend who has a Bushy said to get the AR-15 that will handle or chambered for 556 that way I can shoot both 223 and 556 ammo.? (Then this salesman at the gun shop said "if you get a gun chambered for 556 you may have a bunch of trouble with ejection the shell using 223 ammo!") I know you CANT shoot 556 in a gun marked 223 but you Can shoot 223 in a gun marked 556 cause 556 is beefed up and a more power full shell. I have a S&W 357 mag. pistol and I have no trouble shooting 38 special ammo But you could never shoot 357 mag. ammo in a pistol thats a 38 special.Hope this all makes sense , Iam new to the AR world and want to find out all I can befor I make the move..Thinking Stag,Bushy or Colt???
  2. JASV.17

    JASV.17 Prime Example

    Jul 10, 2007
    223 in 556, no problem

    556 in 223, problem.

  3. F_G


    Jan 11, 2010
    Crown King, AZ
    All of my AR's are chambered 5.56, but shoot .223 just fine.
  4. sarge

    sarge Millennium Member

    Jan 26, 1999
    90.44.1W 35.48.4N
    That's the key words... :whistling:

    You'll do just fine shooting .223 in a 5.56 rifle.
  5. djegators


    Mar 1, 2009
    Tampa, FL
    One other point on this subject, don't pay much attention to the markings on the lower, go by what is marked on the barrel. Not very many .223 barrels these days anyways, but you need to know.
  6. F_G


    Jan 11, 2010
    Crown King, AZ
    Good point, on my older Colt H-Bar the receiver is marked .223 Rem, but the barrel in front of the FSB is stamped 5.56 NATO.
  7. kabob983

    kabob983 "Mostly" Dead

    Jun 27, 2005
    Birmingham, AL
    +1, was he trying to sell you a .223 marked upper?

    5.56mm ammo is pretty much identical size-wise to .223, it's just loaded hotter (there's a few minute differences in dimensions but it's tiny). The issue is that the shorter leade on the .223s isn't designed to handle the more powerful ammunition and can damage the rifle. A 5.56mm barrel with a longer leade will handle low-power ammo with no issues.
  8. internal


    Feb 9, 2006
    Not only that, you got guys like me who never keep a rifle stock.
    LOL one of my AR's has a RRA lower and a bushmaster upper.
  9. kabob983

    kabob983 "Mostly" Dead

    Jun 27, 2005
    Birmingham, AL
    Not all that uncommon. For a while I had a BCM upper on a CMMG lower.
  10. JBaird22


    Nov 18, 2005
    I would guess he had an AR in .223 he was trying to unload and thought "Here's my buyer." You are correct in your original assumptions and there is no problem when shooting .223 in a 5.56 barreled gun. It doesn't recoil as hard or make as much noise but I have shot some pretty low powered stuff out of my gun and it functions fine. Much like your .38 special/.357 mag analogy.
  11. Constructor

    Constructor Moderator

    Dec 10, 2009
    The brass of both the 5.56 and .223 are the same size.
    The difference between the chambers is the length of the leade and the diameter of the neck of the chamber and the leade.

    Attached Files:

  12. Kentak


    Jan 8, 2006
    Central Ohio
    There is some truth to what the salesman told you, but it's unlikely to make much of a difference. To the extent that *some* .223 ammo may be at the low end of acceptable pressure standards, and to the extent that a *specific* 5.56 rifle might be built or setup in such a way as to demand more from the ammo it's fed, the two coming together may not be a perfect marriage. The result could be short stroking and resultant extraction and feeding problems.

    That's hypothetical--in the real world, most shooters with 5.56 seem to do okay with .233 ammo. If problems arrive, the answer might be just to use a different ammo that gives acceptable performance.

    Keep in mind, for casual range use or plinking, low cost of ammo might be a higher priority than 100% reliability. A few feeding problems might be acceptable. When your gun is assigned to hunting or defensive purposes, you'd probably have the "good stuff" loaded in the mags (meaning ammo you know from experience is reliable).
    Last edited: Mar 30, 2010
  13. Glockphobia

    Glockphobia NOT!

    Apr 30, 2005
    Chapin,S.C. BM lower and a DD upper with a armalite barrel w/ a rra bcg.

    but yea, shoot all the 223 out of your 556 that your wallet can afford:wavey:
  14. Briley9


    Aug 29, 2005
    I have an 18" SS barrel that's marked .223 Wylde 1:8, are these 5.56 safe?

    Also, are SS barrels the only ones to be chambered in .223 Wylde?