Riser for Bushnell TRS-25

Discussion in 'AR-15 Discussion' started by jgand72, May 11, 2012.

  1. jgand72

    jgand72 New Member

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    Hey all,

    I just received my Bushnell TRS-25 red dot in the mail. However, I am up at school and do no have my rifle with me. So my question to you all is: Does anyone know what size riser would give me a 1/3 co-witness on a flat top AR with the A2 front sight post? I was thinking a 1", but I wanted to get some of your opinions. Thanks!
     
  2. JTJ

    JTJ Well-Known Member Supporter

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    3/4" will give you a center co witness with the dot on top of the post.
     

  3. jgand72

    jgand72 New Member

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    Awesome, so I'll go with the 1". Thanks!:cool:
     
  4. connectegr

    connectegr New Member

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    Why such a high riser? I am mounting a similar Sig Red Dot this weekend. What is "1/3 co witness"?
     
  5. purehavoc

    purehavoc New Member

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    [​IMG]
     
  6. connectegr

    connectegr New Member

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    I was planning to use "absolute cowitness", iron sight and red dot both centered on top of post. What is the advantage of using the lower 1/3?

    If I use absolute cowitness, is a riser necessary? Is so, how much?
     
  7. purehavoc

    purehavoc New Member

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    its really personal preference , I prefer the lower 1/3 because when I use the RDS I dont have all that sight taking up the whole sight picture . and when I do need to use my irons my RDS wont be on anyway . Either way I have more sight picture thru the RDS with lower 1/3 . again its really personal preference
     
  8. Quentin

    Quentin New Member

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    I also use the bottom 1/3 cowitness for the reasons purehavoc stated. I can look over the irons and just use the dot or look through the aperture and lollipop the dot on the front sight. One disadvantage of absolute is the red dot appears to dim when looking through the aperture - this is very noticeable to me.
     
  9. jgand72

    jgand72 New Member

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    When I had a Bushnell Holosight, though it was definitely usable, I was not crazy about having the front sight take up much of the picture. I feel that if I am using a red dot, I am using it for the dot, not the front sight post. Everyone has they're preference, I just want to try out the lower 1/3 and see how I like it.
     
  10. jgand72

    jgand72 New Member

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    Oh and another question, which may be a stupid one, but will I need a cheek riser? I have no experience with using risers.
     
    Last edited: May 11, 2012
  11. Quentin

    Quentin New Member

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    I doubt it, just the 1" riser for bottom 1/3...
     
  12. connectegr

    connectegr New Member

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    Is a 1/2" riser enough for absolute cowitness?
     
  13. JTJ

    JTJ Well-Known Member Supporter

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    The TRS25 takes a 3/4". A 30mm will take a 1/2".
     
  14. connectegr

    connectegr New Member

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    I have sig STS 081. Does that need 3/4 for center cowitness?
     
  15. Quentin

    Quentin New Member

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    Does it have a standard AR rail and sight height? If so that should work.
     
  16. connectegr

    connectegr New Member

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    No luck finding a 3/4 riser. Bought a 1/2 riser, but it appears closer to 3/4. And it lined up perfect cowitness. No for a few hundred rounds down range. Thanks for the input.