Shooting 5.56 in a .223 Chamber

Discussion in 'Technical Questions & Information' started by 4 eyed six shooter, Nov 12, 2004.

  1. 4 eyed six shooter

    4 eyed six shooter New Member

    Jun 21, 2003
    Teton Mountains, Idaho
  2. Marlin

    Marlin *TFF Admin Staff Chief Counselor*

    Good information, John.

    Thanks for bringing it to our atttention.

  3. ironsight65

    ironsight65 New Member

    Apr 15, 2003
    Thanks for the post. I always thought they were the same.
  4. Glocker

    Glocker New Member

    Oct 17, 2004
    Have there been any known instances of damaged rifles or injury associated with firing 5.56 in rifles chambered for .223?
  5. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    I have heard of two instances at our range where a shooter with a 223 was using military brass (5.56) and hot rodding them. The pierced primers resulting from this stupidity caused burns from the gas exhaust through the action. It is dangerous.
  6. And here's the deal.

    The SAAMI bulletin came out in 1979. There are a few differences between the chamber specifications of .223 Remington and 5.56mm NATO. The difference is in the chamber throat. The military chamber has about .080" longer leade (or throat/freebore). The problem is that if you feed 5.56mm NATO cartridges into a tightly-throated .223 Remington chamber you can jam the bullet nose into the start of the rifling which can increase chamber pressures. Some 5.56mm is loaded hotter than commercial .223 as well (but still well within safety margins of any commercially built rifle), most notably imported ammunition.

    To my knowledge, this has only resulted in some blown-out primers on an anecdotal basis with known tightly-chambered guns.

    The fact is that the differences between COMMERCIAL .223 chambers exceed the difference between the SAAMI .223 and 5.56mm. CZ vs Remington 700 vs Ruger vs whoever all are throated a little differently. Check with your manufacturer to see how your rifle is throated, or have a chamber cast made to include the throat. You'll find that most manufacturers have increased the throat on their rifles to accomodate the longer bullets currently in vogue, and thus have largely eliminated the problem. Earlier rifles chambered in .223 with the slow twist rate specifically for the 50-52gr bullets are the most likely to have the short throat.
  7. Glocker

    Glocker New Member

    Oct 17, 2004
    I was referring to factory ammo, rather than handloads.

    LIKTOSHOOT Advanced Senior Member

    Apr 26, 2001

  9. ibtrukn

    ibtrukn New Member

    May 13, 2001
    central N.J.
    I think Phishie rams 458's thru his dubble duces, thas Y he gets all them tree rat kills (he says) :cool:
  10. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    So called "factory" ammo is .223 Remington, not 5.56mm. The 5.56 is MILITARY ammo and can usually only be had as surplus or cheap imported military ammo. I have never seen any commercially SOLD, boxed and labeled 5.56mm that was not military to begin with. Someone correct me if I am wrong.
  11. Glocker

    Glocker New Member

    Oct 17, 2004
    Perhaps instead of calling it "factory" I should have said ammo that hadn't been hot-rodded since the cause of the pierced primers and subsequent injury was likely due to the hot handloads, and not simply the use of 5.56 in a .223. Would it have happened had the 5.56 not been hot-rodded? I don't know.

    I'm not advocating the use of 5.56 in .223....just trying to learn if anyone knows of a case of a rifle or shooter actually being damaged or injured due to doing so.
  12. ryan_marine

    ryan_marine New Member

    Aug 4, 2004
    If someone can tell me different please do so.
    We were tought, told, and I have seen it shot across a crony, that the m16 using 5.56mm were in the 3250fps range.

    My 223 700VLS shoot all day in the 3300fps and that is with a mild load. This is with the same weight of bullet.

    Can some one tell my why that it is said the 5.56 round are to much velocity and preasure. I have never heard of 5.56 too much for 223 but I have been told that some 223s are too much for the ol M16 to handle.

  13. inplanotx

    inplanotx Active Member

    Jan 28, 2002
    Your question is answered above by CG and read the original article from the first post!
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