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Location: Minnesota,
Joined: 08/28/2004
Posts: 259
Shooting down hill

The argument at the shop is that the shot should be aimed 11/2"higher on the target when shooting down hill.( for argument 100yd shot at whitetail.) Two of us say 100yds is 100yds what ever way you're shooting. The boss says you should. any input??

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Location: Nova Scotia
Joined: 08/17/2002
Posts: 1762
Shooting down hill

At a hundred yards the difference is so insignificant that you need not worry about it. Its going to hit where you aim even at an extreme downhill shot @ 100yds. 300, 400 yds and its a different story.

Location: Minnesota,
Joined: 08/28/2004
Posts: 259
Shooting down hill

Thats what I thought. Now if I can explain this. Nope can't. Need to draw a picture.I'll be back

Location: Minnesota,
Joined: 08/28/2004
Posts: 259
Shooting down hill

here is the art explaining one theory

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Location: Florida,USA
Joined: 08/21/2003
Posts: 1566
Shooting down hill

Hey million, I' ve seen your work on the Discovery Channel !!! Inside some caves.............. Big smile

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Joined: 10/30/2004
Posts: 117
Shooting down hill

The short answer is that uphill OR downhill you correct for the horizontal distance of the shot. On an extreme angle at 100 yards of up or down slope, if you measured the horizontal distance it might be 90 yards. Not much if any correction.

I believe the actual formula is Asquare x Bsquare= C square. Its a right triangle formula. If you envision a right triangle, consider this. Ignore the vertical line. Now look at the upslope line. If that is 200 feet remember that. But forget it. Now look at the bottom or horizontal distance-- If thats 150 feet-- thats the distance you are shooting.

You correct for horizontal distance, not slope distance.

Boy thats hard to try to explain.

Couldn't see the pictograph well enough to comment.

Jeff

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Location: Denver, Colorado
Joined: 03/07/2004
Posts: 57
Shooting down hill

The key to remember here is the principle of gravity, and that a bullet does not travel in a straight line but rather an arch. When shooting down hill one must aim low because of the fact that gravity has less time to do its work on the bullet before point of impact. The bullet will will be in a higher path of trajectory than if it were shot on a flat plane over the same distance. When shooting downhill the bullet may in fact be traveling over 100 yards (of ground distance), but due to the incline and the relative flat plane of gravity, it may have really only traveled 75, if we remember the ballistics of the cartridge in question we will know that it is still in its arch flight path and therefore is still high,(so aim low). Its basic physics, check out a textbook from the library or just go to the local high school and have the physics teacher/football coach draw it on the chalkboard for you.

The only practical application this holds is if you are shooting at an animal from a cliff or down into a steep valley.

Location: Minnesota,
Joined: 08/28/2004
Posts: 259
Shooting down hill

my head hurts

Val
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Location: Torrance, CA
Joined: 09/23/2004
Posts: 6
Shooting down hill

I'm trying to post a diagram from another forum that shows it pictorially

The picture shows that the actual horizontal distance to the target on a steep uphill or downhill slope is less than the actual distance to the target. Therefore, hunters tend to shoot too high at a target at a distance on a steep slope because the horizontal distance is shorter. The horizontal distance determines the bullet drop due gravity. Since the horizontal distance is much shorter than the hunter perceives he compensates for too much bullet drop and shoots too high.

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Location: Minnesota,
Joined: 08/28/2004
Posts: 259
Shooting down hill

now my head really hurts
lol

bitmasher's picture
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Shooting down hill

As a practical matter, assuming you are shooting a high velocity cartridge, Chester is right (at 100 yards it doesn't matter much).

The question becomes more interesting if your shooting a slower round (muzzleloader, bb gun, an arrow) or one that sheds velocity fast (12 gauge slug, bad BC), because the flight path is more parabolic (curved/arched) when properly sighted.

In either case you should hold lower on the target (not higher), how much lower is going to depend on the sighted-in flight path on a zero angle shot.

What Val and others have shown, while correct, is only part of the story. In other words, it is true that 100 yards on an angle is not the same as 100 yards without the angle, because the downward pull of gravity has a shorter distance to work. This is geometry, but there is more to the story.

The other part of the story is the curvature of the flight path changes (sometimes significantly) with the shot angle. Meaning that a zero angle shot will be less "arched" than a 90degree shot straight up in the air. Understanding exactly how much the curvature is changed requires vector analysis and knowning how the gun is sighted in at the zero angle.

The reason the curvature changes is because the angle between the bullet and the downward gravity vector is changing with the shot angle, and the fact that a correctly sighted-in gun is not perfectly parallel to the ground.

Clear as mud? I wrote up a post some time ago that discusses what controls how "flat" a cartridge/bullet combo shoots here (Why a bullet shoots flat or doesn't. Ballistics 101). Understanding, flat shooting is important, because if every projectile shot perfectly flat, shot angle would not matter at all.

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