Riser Height?

Discussion in 'AR-15 Discussion' started by pawjr74, Apr 19, 2013.

  1. pawjr74

    pawjr74 New Member

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    What do you think would be the lowest riser that would either co witness the A2 front sight or clear it? Would a 1/2 inch riser be high enough? I'm running a cheappy non magnified red dot 40mm. I don't like the riser I'm currently running as the MBUS won't fit on the rail with it on there. I'd like to go a little lower if I can. This riser easily clears the front sight. (I can still see the front sight through the red dot with this current set up)
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  2. highpowerguy

    highpowerguy New Member

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    The a-2 sight height is 2.25 if I am not mistaken measure from the center of your optic to where it meets the top of your picitany rail and then subtract that from 2.25 and that will give you the height of the riser you need.
     

  3. pawjr74

    pawjr74 New Member

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    Thanks for the info. I'll check it out.
     
  4. highpowerguy

    highpowerguy New Member

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    Actually I am a little off on that. The sight height is 2.25 inches from the bore line not the top of the rail, you also have to subtract the height to the top of the rail which is about 1.2 inches. So you actually need to subtract the height if you optic from 1.05 inches to get a perfect co-witness however one inch will work fine. Sorry about that I wasn't thinking it all the way through probably shouldn't make forum posts before noon.
     
  5. pawjr74

    pawjr74 New Member

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    Went with a 1/2 inch riser and it's now co-witnessed. Thanks for the help. I know it's a cheap WM red dot...next rifle I'm going to build and it will be upgraded :)
    [​IMG][​IMG]
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    Last edited: Apr 21, 2013
  6. Quentin

    Quentin New Member

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    That first riser was about 4" long! No wonder there wasn't rail left for the MBUS!
     
  7. pawjr74

    pawjr74 New Member

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    Ya, I figured that out about 5 seconds after installing it! LOL
     
  8. Quentin

    Quentin New Member

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    Yeah, not making fun of you... I've got one of those things stuffed in a drawer somewhere, too! :D