20 MOA base interferring with cosine indicator?

Discussion in 'Long Range Scopes and Other Optics' started by str8flite, Aug 24, 2009.

  1. str8flite

    str8flite Member

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    Jun 8, 2009
    Has anyone noticed any inaccuracies when using a cosine or angle indicator mounted to a 20 or 40 moa base? Since the mounting surface of the base is at an angle in relation to the centerline of the barrel, each cosine or angle reading starts off wrong. After some quick trig I figure the base and the barrel differ by about 5.5 vertical yards at 1000 yards. This is only an angle difference of 0.318 degrees. I know its minuscule, but with so many detail oriented readers and shooters on this forum have any odd effects been noticed?
     
  2. AJ Peacock

    AJ Peacock Well-Known Member

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    Can't you just turn the ACI and make it level with the action. Regardless, 20moa or even 40moa is less than one degree, you typically can't read to that fine of graduations (or estimate the angle) anyway in the field.

    AJ
     

  3. azsugarbear

    azsugarbear Well-Known Member

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    Sep 20, 2005
    Ditto.

    Just compensate by rotating the ACI back so that it reads level or zero when the barrel is level.
     
  4. Jay Kyle

    Jay Kyle Well-Known Member

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    Jan 6, 2002
    Loosen the screw in the middle of the ACI, put a cleaning rod into the barrel and hold a level on the rod to level the barrel, then adjust the ACI until it reads Zero, then tighten the screw.