scope cant compensation

Discussion in 'General Discussion' started by wildchild, Feb 11, 2011.

  1. wildchild

    wildchild Well-Known Member

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    Anyone know what the correct amount of scope cant one needs to correctly stay ahead of bullet spin drift. For example if my rifle tends to shoot about 1.5" to right at 500 yrds with no wind should I be able to shoot at a hundred yrd target and put in 8.75moa or 8 3/4" high and be 1.5 to the left of the vertical line.
    Guess really what im look'n for is not have to compensate turn'n windage nobs to the left for the spin drift.\
    After thinking about what i posted I prolly only need about 1/4 to left at 100yds of compensation that would put me about 1.25 to the left at 500.
     
    Last edited: Feb 11, 2011
  2. paphil

    paphil Well-Known Member

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    The gun needs canted to the left by 3 degrees. To get there, cant the scope to the right 3 degrees and then mount the scope level with scope straight up and down.

    After testing........

    This does not work, The scope itself must be canted 3 degrees left!
     
    Last edited: Apr 18, 2011

  3. load

    load Well-Known Member

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    canting may get u close but it will bring a bunch of other issues. for example now your windage adjustment has vertical movement same with the good old "kentucky windage".
    it is more accurate to leave the reticle plumb and to know the spindrift then to dial or hold for adjustment. gun)
     
  4. paphil

    paphil Well-Known Member

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    Vertical change for 3 degrees is less than 1/8 inch. I'll give up that to get rid of 10 inches of horizontal. Maybe make every thing plumb and shoot the ladder test at100 to verify and then use a scope level rotated 3 degrees to play with to see if rotating works for you.
     
  5. load

    load Well-Known Member

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    until you try to shoot in a 15 to 20 mph wind at 1000+ yrd. you'll end up inches out + inches for vertical wind effect u can no longer accurately adjust forgun)
     
  6. paphil

    paphil Well-Known Member

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    I played around with a couple of guns and found that having the scope mounted crooked or canted in relation to the gun does not give the desired results. As long as the scope is held vertical while shooting, the gun will shoot a vertical string on the ladder test at 100 yards. The only way I could get the group to move left at the top of the ladder was to cant the scope. By rotating my scope level to the right 3 degrees, a little over 1/2 bubble, I got the gun to shoot dead on at 100 and 1 inch left of the line when cranked up to 1000 . This makes you feel like you're tilted left when looking through the scope, but you are using the scope level to shoot. So my conclusion is to mount the scope on the gun straight and rotate the level. Also this avoids loosening the scope.
    Each gun and bullet will be different and the slower lower BC bullets with higher arcs to reach 1000 yards will take less than 3 degrees.