proper sight hight with tapered bases

Discussion in 'Long Range Hunting & Shooting' started by Russ M, Jan 21, 2009.

  1. Russ M

    Russ M Well-Known Member

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    when you have tapered bases what is the proper way of measureing sight hight with tapered bases. i am using the leupold bore sighter, at first i had strait bases on my gun and the leupold bore sighter put me with in a couple of inches of bulls eye then after in stalling my tapered bases i used the same procedure (1/2 out side of objective + hight above bore + 1/2 barrel directly under objective), what i am wondering is if i should use thous numbers and knowing my bases are 20 moa to take the hight above the bore at the center of the scope ?
    thank you for your input
    p.s. i wasn't sure were to start this thread so i thought this is were most people look, for the future were should a thread like this go?
     
  2. jmason

    jmason Well-Known Member

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    Russ I'm far from an expert but I think your procedure is sound.
     

  3. Buffalobob

    Buffalobob Writers Guild

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    Depending on whether it is a long action or a short action it takes about 0.001 inches to give 1 MOA, IIRC. So if you have a 20 MOA base you would have a difference of 0.02inches between the front and rear of the base. In my way of thinking, I am not going to lose any sleep over this trivial of a number

    Somewhere back in the far crevices of this forum, I have exactly calculated this number as has a guy named ABINOK.

    A good place to put optics questions is the Optics forum or in the case of this question it could have been the Ballistics part.
     
  4. Russ M

    Russ M Well-Known Member

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    yes that is true that over the action it is a small amount but then when you take that same angle and go over the distance of the barrel i have a 26" so lets use that number the difference now becomes .145" and because of the bore siter i am using that is enuf to put me out at 100 yards by 7 " atleast that was my result
     
  5. Buffalobob

    Buffalobob Writers Guild

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    Well, that's true. I did not understand the real question you were asking.

    In general terms, 1.0 MOA is 0.000278 inches per inch so at 26 inches with a 20 MOA base you would have been off by 0.145 inches at the end of the barrel.
     
  6. Russ M

    Russ M Well-Known Member

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    yes i seem to have that problem of not being able to put things in to words so that other can compeletly under stand what i am trying to say and i guess i answered my own question while i was at it. thank you for your input, do you think that that little bit might afect how much a ballistic computer will tell you to adjust or in that case is it just a minute amount not to worry about
     
  7. Buffalobob

    Buffalobob Writers Guild

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    Depending upon many things such as velocity and BC, but just as a reference point--- 0.1 inch error in scope height gives you a 1 inch error in bullet impact at 1000 yards. If you use real drop data to calibrate your ballistic computation then the error becomes smaller and may be at a different point. In other words, I try to fit my drops more carefully at the longer ranges than the short ranges, so I would tend to make the problem even smaller just by using real data.