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Thread: Sight help please

  1. #1
    Boolit Master
    Lefty SRH's Avatar
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    Sight help please

    I recently mounted a Lyman 66A receiver sight on my M94 30-30. I using the factory bead front sight thats either .310” or .315” (bottom of dovetail to top of bead) tall. I plan to replace the front with a Sourdough partridge but want a little shorter front in order to lower the rear. The rear is kinda high right now. The gap from the top of bolt to the underside of the windage bar is .137”
    If I use a .260” tall front thats a difference of .050” from the factory (keeping it simple). Do I just adjust the lower .050” to theoretically keep the same zero I have now?

    If Im wrong on this, what height front do I need to lower the rear about .050”-.060”?
    Last edited by Lefty SRH; 01-14-2020 at 09:24 PM.
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  2. #2
    Boolit Bub 1006's Avatar
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    I think you just need to go down the same amount on each sight.

  3. #3
    Boolit Master pietro's Avatar
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    .

    If you lower the receiver peep sight as low as you want it, then shoot it at 100yds and measure how low it shoots, you can calculate the proper height front sight needed.

    After shooting:

    1.Measure your Sight Radius.
    2.Multiply your Sight Radius times your Impact Distance (the measurement of the POA to the POI)
    3.Divide your Target Distance in inches

    Last edited by pietro; 01-15-2020 at 03:00 PM.
    Experience is a wonderful thing - It lets you recognize a mistake, when you make it again.

  4. #4
    Boolit Buddy
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    Quote Originally Posted by pietro View Post
    .

    If you lower the receiver peep sight as low as you want it, then shoot it at 100yds and measure how low it shoots, you can calculate the proper height front sight needed.

    After shooting:

    1.Measure your Sight Radius.
    2.Multiply your Sight Radius times your Impact Distance
    3.Divide your Target Distance in inches

    I've seen this formula before - but just wanted to clarify. For a 15" sight radius at 100 yards that is 2" off the mark, is it:
    15"x100(12"x3')
    _________________
    2"
    ??

    Thank you.

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  5. #5
    Boolit Mold
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    If you come down the same front and rear zero will remain same. At 100 yds with 15 inch sight radius each .001 difference in front sight will change impact .240 inches at 100 yds. 100 x 36=3600 divided by 15=240 x .001 = .240

  6. #6
    Boolit Master

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    If a shorter sight is needed, why not just use a file?
    To lazy to chase arrows.
    Clodhopper

  7. #7
    Boolit Master
    Lefty SRH's Avatar
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    Thanks for the help guys.
    I cant and dont want to use a file. That would mess up pre-64 original parts. The original sight is a bead type. A file would ruin it.
    Sure, you can file down a Sourdough Patridge but then you are reducing the size of the brass insert at the top of the blade.
    Last edited by Lefty SRH; 01-16-2020 at 08:15 AM.
    "In GOD We Trust"

  8. #8
    Boolit Master
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    Confused by the 15" sight radius, would have thought the distance from front sight to rear of a receiver on a M94 would be at least 24".

  9. #9
    Boolit Master
    Lefty SRH's Avatar
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    Its actually 22.5”
    The 15” sounds like it measured to the factory buckhorn.
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BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
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