GUN Does anyone have a chart that shows 556 muzzel velocities

Discussion in 'On Topic' started by TwistedMind, Jan 22, 2009.

  1. TwistedMind

    TwistedMind New Member

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    from different length barrels?

    I had intended to do a 7" 9mm ar

    but for the cost of the magwell conversion I could pay for my SBR stamp. Plus, a RRA 9mm uper is going to take 8 months from date of order... So I am contemplating 556 sbr 7" barrel.

    I'm concerned about super low velocities though.

    Any help at all is appreciated.
     
  2. yar1182

    yar1182 New Member

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    don't forget to factor in the cost of ammo. The 9mm is way less expensive
     
  3. Keesh

    Keesh New Member

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    The good thing about AR lowers is that you can do a 5.56 and 9mm. One of my friends shoots 5.56, .22LR, and 9mm all through different uppers. I say build the 5.56 one now and worry about the 9mm later.

    Here's a great resource with .223, I assume you could push it a little more with 5.56 brass:

    http://www.accuratereloading.com/223sb.html
     
  4. I believe that .223 brass actually has more case volume than 5.56 brass. The 5.56 is thicker walled.
     
  5. Keesh

    Keesh New Member

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    I think you're right. I haven't started reloading .223 or 5.56 yet so I'm dumb on the subject.
     
  6. yar1182

    yar1182 New Member

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    223 is more accurate than 556
     
  7. Are you talking about less tendency toward vertical stringing due to more uniform case volume? I imagine that if you're loading for maximum accuracy you'd cut the primer pockets and ream the flash holes either way. You could always weigh your cases and toss ones that are significantly different. You can also measure wall thickness. I can't see how one case is "more accurate" than another other than one simply loading a bunch of cases without any real prep or sorting. In that scenario, I could see how commercially sold .223 cases would be more consistent than military 5.56 cases.
     
  8. Soybomb

    Soybomb New Member

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    for what purpose? defense?
     
  9. Painkiller

    Painkiller The Synarchy of Molten Bones

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    7" ar's are really loud, have pretty low velocity's and you can't use suppressors on them. None of the major companies will warranty their cans being used on them.
    most use pistol length gas systems which means the gas pressures are really high.
     

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