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Thread: shooting downhill

  1. #1

    shooting downhill

    A quick query for those with experience or ballistic calculators:

    Assume a 175m shot with a 100gr .243, shooting downwards at an angle of 30 degrees. Rifle zeroed for 100m.

    If the point of aim was dead on, where is the shot likely to go?

    I'm assuming there won't be much difference, but it should go a little high?

    Thanks,

  2. #2
    simple way to remember is up or down you are effectively shooting the horizontal distance

    imagine a right angle triangle with the right angle at the horizontal




    your target distance is 175yds (A to B)

    effective distance is 152yds with a 30deg down angle (A to C)

    http://www.cleavebooks.co.uk/scol/calrtri.htm

    might shoot a little high in this case but not much

  3. #3
    You'll be low, but not enough to matter.
    Brian.

    Just because you are paranoid, doesn't mean they aren't out to get you......

  4. #4
    I seem to remember an article in Stalking Rifle recently that investigated just this phenomena, the conclusion much to my surprise was that, at stalking ranges with the likes of a .243 there was so little effect that it wasn't worth worrying about.
    dcg

  5. #5
    Quote Originally Posted by Claret_Dabbler View Post
    You'll be low, but not enough to matter.
    It will never impact low. Always higher when shooting up or downhill. But it will be such a neglegible amount I wouldn't give it a second thought.

  6. #6
    main thing to remember is you are looking down on the animal and they are three dimensional therefore aim for the heart means aiming higher on the body than a horizontal shot

  7. #7
    Quote Originally Posted by jubnut View Post
    It will never impact low. Always higher when shooting up or downhill. But it will be such a neglegible amount I wouldn't give it a second thought.
    Do you think?

    Rifled zeroed at 100m striking a target 150 horizontal metres away won't be a little low? Gravity still applies, it's effects are just reduced a bit by the angle above or below horizontal.

    However, we are both right, it will be too small to notice.
    Brian.

    Just because you are paranoid, doesn't mean they aren't out to get you......

  8. #8
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    Gravity works ONLY on the HORIZONTAL distance that the object travels.

    With the obvious caveat that if you fire at an object such as a ballon one mile up drectly above you in the air whilst you wouldn't add any "height" to your sights but shoot "point blank" that the bullet would inevitably run out of steam as it were and be pulled back to earth.

    But conversely if you wanted to assassinate Arthur Scargill at the bottom of a ten foot wide eight hundred meter deep mineshaft you shoot as if he was also "point blank". In other words straight vertically down and NOT with with eight hundred metre sight setting put on your 'scope.

    They taught that even as early as the 1900s in Army Training Manuals. I guess all that fighting on the North West Frontier. They don't teach it, AFAIK, in today's army manuals. Lost riflecraft knowledge!

    So if you stand on a tower and throw a brick at a man standing one hundred yards below (it's first level Altitude 95 of the Eiffel Tower) and twenty yards away from the base of the tower you only need enough force (from you) to throw the brick that twenty yards distance and not enough force to throw the brick one hundred and twenty yards distance. Or whatever the distance is on the long side of your triangle.

    So you'd basically throw it with your effort as if he were standing on the same level as you but "in mid air" twenty yards away. Gravity will carry it the one hundred yards down for free!

    So to the OP's question you take a aim or a sight setting based on the "b" distance alone on his triangle.

    BEWSHER 500 is right on the money.
    Last edited by enfieldspares; 07-03-2013 at 21:19.

  9. #9
    Using Norma 243 100gr soft points as referance data your poi firing at a target 175m away at a 30deg down angle would be approximately 1" low
    Last edited by Mr Lewis; 07-03-2013 at 21:24.

  10. #10
    Brewsher is correct with the geometry but the fact is that in Mungos example the rifle is zeroed for 100m so it will be hitting slightly low over the 150m 'ish distance over which gravity is acting on the bullet.

    One thing I think that we all agree on is that it won't make a worthwhile difference either way in this example.

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