Range finder question

[BTF]

I have a Halo range finder Z10XCA which I purchased primarily for archery but have been playing with it lately practicing longer rifle shots out to 400 yards in a range type setting.

When I use the angle mode pointing it up hill or down a canyon the distance displayed is shortened a fair bit from the actual yards, depending on the angle obviously.

Does anyone here have shooting experience with range finders in angled positions, and do you find the calculated range for shooting up or down steep grades accurate. i.e.: actual yards is 400 but the steep up hill grade is calculated at 350 with the range finder switched to this mode. Do you trust the range finder and shoot at the target aiming as if it was 350 yards?

I haven't found a good spot to field test this yet but just curious what others have found.

[emerson]

The principle is sound. Read Bryan Litz's book "Applied Ballistics" for the answer well explained.

[.264winmag]

Yup it's true. Shooting at incline/decline decreases the 'true ballistic' range, in essence you'll shoot flatter. Has something to do with gravity and stuff, I just trust the rangefinder and voila.

[Bugle M In]

yup...it's accurate.
My dad used to be in the german military.
they had a saying, translated in English...steep up or steep down, always aim low.
The principle behind the range finder and incline , decline angles holds true.
Wish I had it on mine.

[BTF]

Thanks for the input Guys, It is always good to hear what others experience.

[ActionJackson017]

It's trigonometry.. the adjusted distance (ie. base of the triangle) you're shooting is less susceptible to gravity than the hypotenuse your bullet is traveling. I probably butchered that explanation, but it's how I remember it.

[Rob Chipman]

ActionJackson got it right. Shooting up or down means gravity effects the bullet less. Bugle M In's old man's advice holds true.

[HarryToolips]

It's trigonometry.. the adjusted distance (ie. base of the triangle) you're shooting is less susceptible to gravity than the hypotenuse your bullet is traveling. I probably butchered that explanation, but it's how I remember it.
No, it makes perfect sense thanks...I've heard your also supposed to aim lower when shooting either up or down due to the optical illusion ie looks as if the distance to target or object is farther away than it actually is..

[Grumpa Joe]

Yes, AJ is right, it is trig. Here is another way of explaining it.

Your straight line distance is the hypotenuse (the long side) of the triangle. Gravity has effect on the bullet only over the horizontal distance that it travels. The vertical component has no effect so essentially you are shooting a "shorter distance". So shooting uphill or downhill the gravity's effect on the bullet is less than the straight line distance. The greater the angle, the shorter the adjusted shooting distance is. The link below has a visual explanation which may make more sense.

http://www.huntingbc.ca/photos/showphoto.php?photo=32925&title=uphillballistics&cat=500