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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. ObsidianOne

    ObsidianOne Member

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    Dangerous advice. If a gun is marked .223, best to ask the manufacturer. While most of the time they do interchange, the max pressures for 5.56 are almost 8,000 psi higher.
    Some guns, such as a certain model of the Ruger Mini 14, some competition model, is NOT setup to shoot 5.56 and can ONLY shoot .223. Save a gun, life, or limb, call the manufacturer.
     
  2. SwampWolf

    SwampWolf Member

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    ObsidianOne: I've never heard of a Ruger Mini 14 rifle that will not shoot 5.56 ammunition safely. Please provide verification of this "allegation". Thank you.
     
  3. firesky101

    firesky101 Member

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    A quick browsing of Ruger.com shows most mini-14's as .223/5.56, however the target models only say .223.
     
  4. Warp

    Warp Member

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    No, they most certainly are not.

    .223 in a 5.56 chambered firearm, yes.

    5.56 in a .223 chambered firearm...best to avoid.
     
  5. balderclev

    balderclev Member

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    If you are shooting 556 in a Mini-14 or AR-15 you should be fine. They have sloppy actions. A bolt gun is not the same. Shooting 556 in a bolt gun chambered for 223 will sometimes cause difficulty in chambering.
     
  6. winterhorse290

    winterhorse290 Member

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    seems strange. i can order .223 reloading dies all day long but have never seen 5.56 dies for sale.
     
  7. cfullgraf

    cfullgraf Member

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    Dimensionally, 223 Remington and 5.56 NATO cases are identical.

    The differences come from what is in the case and the chambers.
     
  8. Warp

    Warp Member

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  9. Carl N. Brown

    Carl N. Brown Member

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    .223 Remington has SAAMI spex established 1962. SAAMI = Sporting Arms and Ammunition Manufacturers Institute (the European equivalent is CIP Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives ). CIP has standards for .223 Remington are similar to SAAMI but slightly different too. I suspect .223 Remington sporting spex are tailored for bolt action rifles. (I could be wrong and someone will tell me I am.)

    Military contracts determine the specification of 5.56x45mm ammunition which includes the pressure level at the gas port for semi or full automatic firearms. Each different contract.

    My understanding is that the main difference between .223 and 5.56mm arms and ammo is the chamber dimensions (particularly the throat or leade where the bulllet enters the rifling) and the rate of twist in the barrel.

    I have heard most .223 barrels are usually throated for bullets in the 36 to 55 grain range, with twist rate of 1 turn in 12 inches, whereas most 5.56mm NATO is throated for bullets in the 55 to 62 grain range, with typical twist rate 1-in-9 although the first M16 and AR15 rifles were 1-in-12 for the 55 grain.

    Firing the heavier bullets in chambers with shorter leade can cause pressure to go up. Same precaution as loading highpower rifle cartridges with bullets that touch or enter the rifling. Watch the primers for excess pressure signs: if they are observed, stop. True for any caliber, any gun, any lot of ammo.

    I also have heard that for countries that forbid military calibers, firearms are often marked .223 Remington rather than 5.56 NATO with no real difference.

    PLUS there are some AR or Mini14 barrels marked .223 that are truly .223 Remington, but many are actually identical to 5.56mm NATO.

    It's like using +P in a revolver: you won't know for sure unless you ask the manufacturer if the gun or barrel was made for it.

    I have treated .223 and 5.56 ammo factory loaded with 55 grain FMJ as equivalent. Some will tell me not to worry, others will advise me to make sure I have good insurance.
     
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