Sight change equation

Discussion in 'Gunsmithing' started by Plumber, Dec 16, 2012.

  1. Plumber

    Plumber Well-Known Member

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    I've seen this question posted a few times, and would like to help, if I can.
    I put a new receiver sight on my 336 and it shot high with the rear sight bottomed out.
    The first thing I did was, moved the rear sight up one notch, then shot it at 50 yards, with the fastest, lightest rounds I will be shooting. At 50 yards my point of impact will be at it's highest. At closer and further ranges my point of impact will be lower. So I will never need to move my rear sight any lower, only raise it higher. I measured from the center of my group to the center of my target. I was 8" high. I will call this Distance D. The second number in the equation is the Range in inches. I will call this R. The last number is the Sighting radius. Mine was 22.5" (distance between front and rear sights) I will call this S.

    Here is the equation; (D/R)S
    That is D divided by R times S
    In my case that is D=8"
    R=1800"
    S=22.5
    8 divided by 1800= .004444444444 times 22.5= .1"
    My front sight was .370" high. plus .1"= .470"
    I could not find a sight I wanted at .470 so I went to .475"
    (Never go shorter)

    This works for me every time. Just remember the old axiom, garbage in, garbage out. Measure carefully, do the math, and check it twice.

    This also works with a scope, but your sight radius is the distance between the scope rings.
     
  2. Hyphenated

    Hyphenated Well-Known Member

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    Nice info Plumber....I'm gonna copy and paste this to Word.