Do I need to worry about shooting downhill angles?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by sambo3006, Jan 29, 2008.

  1. sambo3006

    sambo3006 Well-Known Member

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    In the area I hunt elk in Colorado, most of my shots are from 200-300 ft above the elk and shots are from 300 yds +. I was considering getting an angle cosine indicator, but I ran some math using the Pythagorean theorem. Assuming I am 300 ft (100 yds) above the elk, when the lasered distance is 300 yds, I come up with a straight line distance of 283 yds. As I increase the distance to target, the difference between line of sight distance and straight line distance gets smaller, assuming the same vertical distance above of 300 ft.
    If my assumption about LOS relationship to straight line distance is valid, I don't think I need to worry about compensating for the difference between the two when I figure bullet drop unless shooting at a much greater uphill or downhill angle then I ever would from that area. Am I correct? What say you guys?

    Thanks in advance,
    Sam
     
  2. goodgrouper

    goodgrouper Well-Known Member

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    Yes, you are correct. But if the angle or distance increases, you will be wanting the ACI.
     

  3. sambo3006

    sambo3006 Well-Known Member

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    GG,
    How far out are you talking? If I am 300 ft above the target, at 1000 yds, the horizontal distance works out to 995 yds. I have no plans of shooting farther than that, need to practice more to increase my current limit of 600 yds. If the angle were significantly steeper, the distance would be much shorter (in that hunting area) and shouldn't make much difference. I do want to learn as much as I can in order to place my bullet as accurately as possible, but I want to keep things simple if shooting at a shallow angle won't change my POI more than a few inches.
    As always, thanks for the good info.

    Sam
     
  4. goodgrouper

    goodgrouper Well-Known Member

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    The difference in correction gets more and more the farther out and the steeper the angle obviously and is also more critical the more "arc" you have in your trajectory. With a reasonably flat shooter, I start to think about the corrections when the distances get out to 500 yards and further and 10 degrees and steeper or a combination of the two. A 100 yard height difference over 1000 yards is not much of an angle to worry about but it pays to run the numbers to find out like you are doing.
     
  5. WWB

    WWB <b>SPONSOR</b>

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    Angle Shooting

    If you are using a rifle chambered in .308, and the target is 300 yards out, and you are aiming up or down on a 45 degree angle, (with no wind) and you do not correct for gravity, you will miss the target high by 8". (theoretically)

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    web: Sniper Tools Design Company - angle cosine indicator
    email: info@snipertools.com
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