Absolute and lower 1/3 co-witness

Discussion in 'AR-15 Discussion' started by drvsafe, May 15, 2013.

  1. drvsafe

    drvsafe New Member

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    I'm looking at buying a red dot or holo sight for my AR and I'm trying to understand the difference between absolute and lower 1/3 co-witness. Can anyone give me compelling reasons to want either of them and which is preferable for range and HD use?
     
  2. AgentTikki

    AgentTikki New Member

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    If you have a fixed front sight, I would highly recommend 1/3.

    In all practicality there's not a huge difference. Its just two different ways to cowitness.
     
    Last edited: May 17, 2013

  3. Jpyle

    Jpyle New Member

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    Only difference if cowitnessing with dot on is the need to reposition head to see sights with 1/3, if scope fails or dot is off there is no real difference. Either way I believe it is just whatever works best for you and whatever mount height gives you the best eye relief and cheek weld.
     
  4. Quentin

    Quentin New Member

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    I also prefer bottom third cowitnessing. It gets the irons low and out of the way for normal RDS use.
     
  5. Planejain

    Planejain New Member

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    I second what Quentin likes. Its there when you need it for a SHTF moment, but out of the way for everyday play shooting.
    [​IMG]
     
  6. TekGreg

    TekGreg Lifetime Supporting Member Lifetime Supporter

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    The only difference, as I understand it, is the riser. If you mount an optic directly to your top rail, it will typically be going right over your iron sights. Place the optic on a riser, and the iron site sight line appears in the lower third of the optic out of the way of the reticle. Either way, you can buy the ~$20 riser and try both ways to see what works best for you!
     
  7. AgentTikki

    AgentTikki New Member

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    I'm gonna add this to my primer......seems to come up constantly...


    Written and produced by Dieselpower @calguns.net.
     

    Attached Files:

  8. drvsafe

    drvsafe New Member

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    Should it matter if I have magpul buis? They're flip up...
     
  9. Jpyle

    Jpyle New Member

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    No, as long as the mount for the RDS places the MBUS in the proper position relative to the dot, I.e. the center of the lens or the lower 1/3.
     
  10. Anna_Purna

    Anna_Purna New Member

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    Magpuls are nice, just dont shoot 3 magazines in a row as fast as you can if you have one on the front or it might do an impersonation of the wicked witch of the west at the end of the movie!
     
  11. purehavoc

    purehavoc New Member

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    You should never mount a plastic sight on a gas block to begin with . :D or meltdown should be expected
     
  12. locutus

    locutus Well-Known Member Supporter

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    I've tried it both ways with a holosight.

    My preference is absolute co-witness.

    I dunno. It just "feels" right to me.:D
     
  13. drvsafe

    drvsafe New Member

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    I run a long stroke piston AR and my tail is full length on the top.
     
  14. okdonk

    okdonk New Member

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    Absolute Co witness for me.. always.