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Thread: Question on 'Clamp-On' AR A2/A3(?) Fixed Sights

  1. #1
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    Default Question on 'Clamp-On' AR A2 Fixed Sights

    I've got a set of fixed rear and front sights. I thought there were DMPS, but don't think so. They are solid sights, but something isn't making sense in the measurements. No, they are not UTG or some other cheap set that I can tell.

    I had installed them on a 16" upper with a 15" FF hand guard and just wanted to test the barrel at 50 yds to see how well it did.

    I set the rear sight up using the RIBZ procedures so 50 yds would be using the rear sight at 6/3 -4.

    The problem comes with the front sight. Using a bore sighted mark out the door window at about 50 yds, even after screwing the front post down all the way, visually they were still about 3' apart at 50-60 yds.

    So I took them off and measured just the sights from their bases where they would hit the upper's rail to the middle of the small aperture and the top of the front sight with the sight back at the 'zero' position of even with the front sight base. There is a 0.280" difference between the two, with the front post being taller... and this is a standard base and post, not the taller post or 'F' base.

    There is obviously no way in tarnation that I can zero the rifle with the front sight post being .245" higher than level, unless this kind of sight can only be used on a railed gas block on a carbine or something.

    Any ideas as to what this is all about? I'm assuming I'm going to have to find a new front sight if I keep this rear sight, which I like because it's got the elevation adjustment capability and I'm thinking about keeping this upper on iron sights.

    Suggestions?

    Thanks,
    Last edited by WoodieSC; 01-15-2017 at 07:33 PM.
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    Foothills Golden Retriever Rescue
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    "Keep your powder dry, Boys!"
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  2. #2
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  3. #3
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    Default

    Sound like your front sight is designed to sit on a gas block and not a top rail of the handguard.

  4. #4
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    Quote Originally Posted by Steelin' Ducks View Post
    Sound like your front sight is designed to sit on a gas block and not a top rail of the handguard.
    This might be it. Some gas blocks have different heights.

    Can you post a pic Woodie?

  5. #5
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    Default

    Quote Originally Posted by Steelin' Ducks View Post
    Sound like your front sight is designed to sit on a gas block and not a top rail of the handguard.
    That was my first thought, but without researching it yet I "thought" they were all designed to be the same height, but apparently not.

    USMC, I'll try to get downstairs yet tonight if I can and post one.
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    Foothills Golden Retriever Rescue
    .
    "Keep your powder dry, Boys!"
    ~ George Washington

    "If I understood everything I said I'd be a genius." ~ 'Unknown'

  6. #6
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    Quote Originally Posted by USMCsilver View Post
    Sure enough. That's the issue. The guy I bought the set from either didn't understand the problem he was having, and didn't say anything about it, and I never thought to ask. Guess I need to get a different front sight since I'm not planning on using a gas block w/rail.

    Thanks, guys.
    Last edited by WoodieSC; 01-15-2017 at 10:24 PM.
    .
    Foothills Golden Retriever Rescue
    .
    "Keep your powder dry, Boys!"
    ~ George Washington

    "If I understood everything I said I'd be a genius." ~ 'Unknown'

  7. #7
    Join Date
    Sep 2004
    Location
    Camden, SC
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    Default

    Quote Originally Posted by WoodieSC View Post
    Sure enough. That's the issue. They guy I bought the set from either didn't understand the problem he was having, and didn't say anything about it, and I never thought to ask. Guess I need to get a different front sight since I'm not planning on using a gas block w/rail.

    Thanks, guys.

    Kinda assumed as much.

    You're welcome!

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