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can my ar 15 shoot 5.56?

Discussion in 'Rifle Country' started by Johnny Lightning, Mar 26, 2013.

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  1. Johnny Lightning

    Johnny Lightning Member

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    I have a bushmaster lower that can shoot both .223 and 5.56 but the rock river upper is the question. I took the hand guards off to find out if there is anything written on the barrel but the only markings are 200C/K? There is a keyhole marking on the upper receiver also but that's all I can find. Thanks for the help!
     
  2. jmr40

    jmr40 Member

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    223 and 5.56 are completely interchangeable.
     
  3. Certaindeaf

    Certaindeaf member

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    Except someone is going to cite a tome how they are not.
     
  4. RainDodger

    RainDodger Member

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    I recommend calling Rock River and asking their customer service.

    Chances are that it's just fine. I'm not going to write a tome about anything, but make sure it's a 5.56 barrel before shooting a bunch of actual 5.56.
     
  5. Rom828

    Rom828 Member

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    If the barrel is marked .223 they are not interchangeable. 556 is loaded to higher pressures and has a slightly different chamber. In your AR your fine but in older rifles use caution.
     
  6. silicosys4

    silicosys4 Member

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    You mean like hornady, Lyman, lee, Sierra, etc...?
    Maybe not a tome, but definitely disclaimers in their data.
     
  7. Bill4282

    Bill4282 Member

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    Bushmaster will tell you that you can shoot .223 in a 5.56 barrel but, due to higher NATO pressures, no 5.56 in a .223 barrel. Google .223 vs 5.56 and you'll find plenty of articles on this subject.
     
  8. C-grunt

    C-grunt Member

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    Many of the Bushmasters we had at work would pop primers when we shot M193 for one qual course.
     
  9. adelbridge

    adelbridge Member

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    pretty sure most RRA barrels are setup to run 5.56. If it was a litigious problem i suspect the industry would have created better safeguards like .38 special vs .357 magnum.
     
  10. firesky101

    firesky101 Member

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    a vast majority of AR uppers are cut with 5.56 chambers and not .223 chambers. .223 chambers exist, but typically on varmint/target specific uppers and even then are usually a special option. As for 5.56 in a .223, I saw an article on here not too long ago where several (6 i think) rifles were tested. In the 2 .223 bolt guns when used with 5.56 ammo pressures in excess of proof loads were achieved. They did not blow up, but I have plenty of .223 laying around to feed to my .223 chambers that I am not going to risk it.
     
  11. paulo

    paulo Member

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    Make sure it's not a Wilde cut chamber.
     
  12. rust collector

    rust collector Member

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    The Wylde chamber is safe for both types

    That's its purpose in life--accuracy coupled with safety. If your gun has a Wylde chamber, you are gtg.

    Nato chambers are designed to ease extraction and function. Nato brass tends to be thicker to stand up to more punishment, but that means you start with a lighter load. There is a difference, it is often overblown, but get the real story and don't rely on scuttlebutt.
     
  13. Hacker15E

    Hacker15E Member

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  14. madcratebuilder

    madcratebuilder Member

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    Lot of FAIL in this thread.

    READ.

    http://www.ar15.com/ammo/project/AmmoOracle_061808.pdf

    Important part.

     
  15. Creature

    Creature Member

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    Concur.

    You could be the next Darwin Award recipient if you shoot 5.56 in a 223 chambered rifle.
     
  16. taliv

    taliv Moderator

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    i think it's been covered pretty well above, but just consider the real problem is likely to come from stacking issues. shooting 556 in your nice clean 223 chamber off a bench is probably not going to blow up. but add a little dirt or a little rain. or a fast firing schedule like a carbine class that gets the gun hot. and then that one round that is a little hotter.

    a side note is that many of the cheaper ARs (which often have 223 chambers or worse, tight 556 chambers) seem to be sort of optimized for the weaker wallyworld ammo and tend to cycle better with it.
     
  17. col_temp

    col_temp Member

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    thanks all and Taliv
    Good point.
     
  18. hentown

    hentown Member

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    I'm pretty sure that all RRAs that aren't chambered in 5.56 are chambered in .223 Wylde, which, as MOST of us realize, is safe for both .223 and 5.56. ;)
     
  19. SwampWolf

    SwampWolf Member

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    The Rock River Arms (RRA) catalog specifies two chambering configurations/options for their AR-15 rifles: "5.56mm NATO Chamber for 5.56mm & .223 Cal." and ".223 Wylde Chamber for 5.56mm & .223 Cal." To the question of "What is a Wylde Chamber?", RRA responds "The Wylde chamber was designed as a match chambering for semi-automatic rifles. It will accomodate both .223 Rem and 5.56 NATO ammunition. It is relieved in the case body to aid in extraction and features a shorter throat for improved accuracy."
     
  20. Fleetman

    Fleetman Member

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    on the same subject but a different barrel...shooting 5.56 in my TC Contender shows signs of excessive pressure....somewhat sticky opening and a very large muzzle flash....I find .223 which is what it is chambered for works better and "feels" better. I have a letter from TC dated 12/83 that says there is no problem firing either in a Contender.
     
  21. 1KPerDay

    1KPerDay Member

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    Several MFGs mark barrels .223 but actually cut the chambers Wylde or 5.56. (ruger minis are one example... the mini "target" model is the only one with a true .223 chamber; all others accept 5.56 without issue).

    Call the MFG.
     
  22. Hacker15E

    Hacker15E Member

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    That's all well...but look at the LuckyGunner test as a counterbalance to that just-by-the-numbers statement, which measured the features of several examples of different 5.56, .223, and Wylde chambers. The important point of comparison in that data is that the variances in measurements between the different makers and examples within a single chamber design that were all over the map, including dimensions that overlapped into the other chamber design measurements.

    Bottom line: the discussion is just not as simple as quoting the 'ammo oracle'.
     
  23. sixgunner455

    sixgunner455 Member

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    If it won't, get it fixed: barrel->gunsmith+correct chamber reamer= /problem.
     
  24. Coop45

    Coop45 Member

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    My Remington 700 in .223 had a very long throat. In this lawyer laden country, I'd almost bet that all production .223 barrels have a similar chamber.
     
  25. mtrmn

    mtrmn Member

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    I'll throw my story in-you decide.

    I bought several parts kits and assembled them on lower receivers. I also have 1 Colt AR. ALL the barrels are marked 5.56. I had pressure trouble with hotter loads in my kit guns but no problem whatsoever in the Colt.

    I added heavier buffers, heavier springs, on and on. Things improved, but the problems were still there. Finally I sunk some money into a Christensen reamer from Michiguns. I ran it through every barrel and it removed a surprising amount of metal from all the kit guns that were ALLEGEDLY chambered to 5.56. Only the Colt passed the reamer test with NO removal of metal. Now ALL my AR's have no problems with 5.56 ammo. What more can I say? There IS a difference in the chamber and it has a very noticeable effect on performance--especially in carbine length barrels. YMMV
     
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