Point of Aim vs. Point of Impact

Discussion in 'Long Range Hunting & Shooting' started by jcmckinney1, Nov 22, 2010.

  1. jcmckinney1

    jcmckinney1 Well-Known Member

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    I have a Remington 700 Long Action Sendero .338 RUM, Zeiss Diavari 6-24x56, Badger Ordinance 0 cant base with .035 in shims under the back base, Badger Ordinance Rings. My point of aim to point of impact is a difference of 11 inches down @ 50 yds. What can I do to achieve max scope elevation adjustments and be dead on at 100 yds. Would a 45 MOA base work better?

     
  2. liltank

    liltank Well-Known Member

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    To achieve what you would like to do, you need to put heavier shims (make sure you shim the front so that it stays linear when tightening your screws) or go to a minimum base cant of 20MOA. 45MOA may be to much and give you a farther zero.

    Tank
     
  3. jcmckinney1

    jcmckinney1 Well-Known Member

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    Thanks Tank. Do you know what .035 inches is in MOA? I was told .010 = 1 Moa.
     
  4. liltank

    liltank Well-Known Member

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    I couldn't tell ya. I am extremely math deficient!:D It would be best to ask a gun smith or a rifle builder.

    Tank
     
  5. edge

    edge Well-Known Member

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    You should be able to get close by dividing 3600 inches ( for 100 yards ) and the distance between scope base screws in inches, then multiply times your shim thickness.

    eg: if the screws are 3 inches apart and you have a 0.010 shim

    3600 / 3 = 1200 * 0.010 = 12 inches.

    edge.
     
  6. Catfish

    Catfish Well-Known Member

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    For it to be that far off I tend to think that you have a problem with the bases you have on the gun. I think you should be able to find bases that would not need shimmed.
     
  7. edge

    edge Well-Known Member

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    I may have missed your point!

    That scope has about 56 MOA of vertical adjustment.
    Where is it set now?

    IMO, for maximum long distance shooting it should be near the bottom DOWN adjustment.
    Personally I would stay at least a few clicks off of bottom to be kind to the mechanism.

    In a perfect world that should mean that you need about 25 MOA+- of cant in the scope.

    If I guess that your base screws are 4 inches apart you would have 3600 / 4 = 900
    Round it off to 25 inches + about 2 inches of drop = 27 inches

    27 / 900 = 0.030 shim

    The world is rarely perfect, but you have a shim in place that "should" have gotten you close. It seems strange that it should be off by 20 inches....unless your scope is not adjusted fully or the distance between base screws is off wildly ( which I only guessed at :) ).


    edge.
     
  8. jcmckinney1

    jcmckinney1 Well-Known Member

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    edge, the scope is set at +1 from bottom/0. I did not want to adjust up to the point of aim with the scope. I wanted to use a base with the appropriate cant in it so that I can fully utilize the 56MOA adjusment in the scope.

    Badger Ordnance measurement between screw hole 2 to hole 3 (front to rear) is 4.5 inches.
     
  9. edge

    edge Well-Known Member

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    It sounds like you need about another 0.025 of shims.

    I would think that a base with built in MOA would be better since you may be torquing the base unless you are bedding the base too.

    edge.