How to Shoot Uphill and Downhill

Discussion in 'Long Range Hunting & Shooting' started by RockyMtnHigh, May 16, 2013.

  1. RockyMtnHigh

    RockyMtnHigh Member

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  2. madman

    madman Well-Known Member

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    Nicely done.

    --md
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    Not too bad.

    Below is a link to an article I wrote a few years back. I think you'll find that it pretty much agrees with what you're saying here.

    The 'How To' of shooting on an incline. - Long Range Shooting - CouesWhitetail.com Discussion forum

    One of the real dangers to the riflemans rule that gets overlooked is that when you set your scope up for a 500 yard shot versus a 900 yard shot due to the angle (say a cosine of .56) the MOA values at those ranges Are vastly different. In other words, .25 MOA per click equals 1.309" at 500 yards and 2.356" at 900 yards. This compounds the problem. A true 500 yard shot may take X clicks to get there but the same amount of clicks are too much for the same shot used in this example where 900 yards is the line of sight but 500 yards is the horizontal distance. The target is still 900 yards away and the click or holdover values need to be used accordingly. That is one of the few reasons that the MOA or MIL * cosine works so much better than the yardage * cosine method. But like was pointed out, if your zero is a given yardage such as 300 yards and your angled shot is 300 yards, it doesn't work. This is why the bore line drop must be considered. Ballistic software takes that into consideration.

    I like to use the illustration of zeroing a rifle at 1000 yards horizontally. Then moving the target 1000 yards straight up. 90 degrees * cosine (0) = 0. The
    Scope is then not adjusted because the math said 0. When you shoot at the target the bullet ends up behind you because the barrel is pointed beyond 90 degrees.
     
  4. cohunter14

    cohunter14 Well-Known Member

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    Wow, very interesting and informative thread and now I feel like a complete dummy! As a long time golfer and someone who is fairly new to long range shooting (over 500 yards), I just assumed that I could use my range finder that adjusts yardages for slope. However, it looks like that won't work because an uphill shot would make the distance farther instead of shorter. So a couple of questions on all of this:

    1) Can I still use my range finder to get me the actual slope and then adjust the numbers accordingly?
    2) Between your two articles, it looks like there are three different ways to calculate the slope, but all provide very different results (especially if you start using the examples out around 1000 yards). So which one is the most accurate out of all of these? Does anyone have any first hand experience in trying all of these methods to determine which is the most accurate?

    Thank you both for the information you provided, great learning experience!
     
  5. CB11WYO

    CB11WYO Well-Known Member

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    Nicely written, thanks!
    I'm a geometry nut so all your examples clicked just fine. :)

    Thanks also for comparing the Rifleman's Rule vs. the Improved version as this had not yet occurred to me.
     
  6. cohunter14

    cohunter14 Well-Known Member

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    I want to bump this up again because I would really like to know if yardage finders that calculate slope actually work for shooting or not...
     
  7. cohunter14

    cohunter14 Well-Known Member

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    I have been researching this because it is driving me nuts. I think everything that Rockymtn and Michael posted in their articles makes sense, but uphill shots should never 'play' shorter than a flat shot. With that in mind, I think this is what you need to do: If the target is above you, then the distance will be the adjacent side of the triangle and the slope distance will be the hypotenuse. Whereas, if the target is below you, then the hypotenuse will be the actual distance and the adjacent side will be the slope distance. Does that sound correct? Maybe that was in the articles and I just missed it...

    Anyway, with all of that said, I think rangefinders that calculate slope do truly work then, which is what I wanted to know :)
     
  8. Michael Eichele

    Michael Eichele Well-Known Member

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    Your bullets will impact high on a sloped shot the same be it uphill or downhill. In both cases gravity's force is acting on something other than straight down on the bullet's bearing surface. Obviously if you fired straight up, gravity is acting on nothing except the nose. Straight down and it's acting entirely on the tail. Either way, they are only going to move in a straight line. The closer to these 'straight' lines the bullets are launched the less they're going to drop in relation to the target.

    You have to remember, the rifle barrel is always tilted up in relation to your target on a horizontal shot. The bullets come up into or higher than the line of sight to hit a target. Aim your scope straight down 90 degrees and fire at a target that is at your scope's zero distance. Will you hit it? No. Why? Because you're aiming too high. The barrel is angled above your target. Likewise, aim your scope straight up. If you fire will you hit your target? No. Why? You guessed it, your barrel is angled too high in relation to the target. From the shooters perspective, the bullets in either case will hit above the targets. Up or down does not matter.

    M
     
  9. cohunter14

    cohunter14 Well-Known Member

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    That still does not make sense though...as I mentioned I have more experience as a golfer than a shooter, so let me use golf as an example. Say you take your flatest trajectory club (a driver) and hit it on a 5 degree upslope and a 5 degree downslope. The downslope shot is obviously going to go farther because the ball will stay in the air longer. Now I know there is more arc in any golf shot than a bullet trajectory, but the same general idea has to apply.

    The same thing applies for a range finder that measures slope...uphill has to play longer and downhill plays shorter. Gravity obviously has it's influence. I don't see how it could work opposite of slope measuring range finders and a golf ball for that matter. I could be wrong, but it just does not make sense to me...?
     
  10. Michael Eichele

    Michael Eichele Well-Known Member

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    Nice example but golf clubs and balls are not apples to apples. In rifles, you have 3 key items with various angles at play. 1: slope angle. 2: scope angle. 3: barrel angle.

    You'll get a handle on this soon.

    M
     
  11. 375fan

    375fan Well-Known Member

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    That has got to be the simplest, easiest explanation I've ever read. Thanks Michael.
     
  12. .284

    .284 Well-Known Member

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    Up or down doesn't really matter ( well it does a little but the distances at which it would matter have way more variables that would overcome any correction we would apply) you are only really concerned with the horizontal distance for your drop and the hypotenuse length of your triangle that you speak of for wind correction and spin drift.
     
  13. RockyMtnHigh

    RockyMtnHigh Member

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    COHunter14, I apologize it has taken me so long to respond. To answer you question directly, the adjacent side of the triangle which is the horizontal distance to the target is the distance most rangefinders give you when they compensate for the angle. I say most because very high tech rangefinders like the BR2 actually provide a full-on ballistic solution. In other words, these rangefinders have a ballistic program built into them and know what bullet your shooting and all sorts of other environmental data.

    But if you look at a rangefinder like the Swarovski El Range, all it is doing to get the corrected distance to the target is doing the cosine math for you and giving you the adjacent side of the triangle which, again, is the horizontal distance to the target.

    You are absolutely correct that if you use a standard rangefinder it will be giving you the hypotenuse or straight line distance to the target. You can then do the math yourself and figure out the adjacent side or horizontal distance to target and then use your method of choice for compensating accordingly.

    I hope that helps.