Calculating true distance to target when shooting downhill

[Alabama556]

Is there a formula for calculating the true distance to a target when the target is downhill of the shooter?

In my case I am setting up a set of long range targets at my farm and the elevation drops 100-200 feet over 0-700 yards.

My rangefinder will give me the angle.

Thanks

 

[308pirate]

Is there a formula for calculating the true distance to a target when the target is downhill of the shooter?

In my case I am setting up a set of long range targets at my farm and the elevation drops 100-200 feet over 0-700 yards.

My rangefinder will give me the angle.

Thanks

If by true distance you mean the horizontal distance, yes there is a formula. It's the geometry of a right triangle.

 

[DocRDS]

Distance is Distance. If you range a target with some sort of tool--that's the true distance.

Shooting at an angle doesn't actually change the distance to the target. It alters the effect of gravity on your bullet (in effect it lessens the pull of gravity on the bullet). One of the ways to deal with this is to shoot dope for an "effective" distance.

 

[Aftermath]

Cosine

www.math.net

 

[MDof2]

Litz just talked about this and posted on it in the facebooks/ab blog, internet's, etc..

Worth a read in the book version as well.

 

[TheOtherAndrew]

Based on 700yd (2100ft) long and 200ft height (up or down dont matter) - got ~6degree angle tops.

Equates to .996 of actual value for LOS distance. 700yd LOS = 697yd actual

So id say just shoot it like a flat range, if you have the 200ft height at say 2-300yd then you may want to worry about it a tad more.

 

[TheOtherAndrew]

Calc angle

Trigonometry Calculator

Calc cosine value

Table of Cos(a)

multiply cosine value by LOS value

 

[Alabama556]

Thanks for the help. It does not seem like it will make much difference given the small elevation change

 

[PinesAndProjectiles]

Maybe look into a range finder that will calculate the distance for you.

I’ve got a Leupold that does it and it was about $200.

 

[Alabama556]

I have a range finder. I was trying to understand the true distance given the drop in elevation.

 

[Baron23]

I have a range finder. I was trying to understand the true distance given the drop in elevation.

As Frank said during a clinic, the Marines told him that when shooting up/ downhill to aim for their balls and you’ll hit ‘em somewhere in the body. We thought that was pretty funny…and true. Lol

 

[Rudy Gonsior]

I always find it funny how much math people are willing to do in effort to calculate something so minuscule, it would be lost well within their actual ability to shoot.

Knowledge is the amassing of information, wisdom is the appropriate application of knowledge in context to a specific set of circumstances.

 

[acudaowner]

 

[ptosis]

The "equivalent horizontal range" has a rather limited scope of application; it is hardly any better than not taking slope into account at all.

The "improved rifleman's rule" is much better.

Gory nitpicking: https://geladen.ch/en/inclined-fire/

 

[DocRDS]

I have a range finder. I was trying to understand the true distance given the drop in elevation.

What do you mean "true distance"

You keep using that term but its not a standard terminology. As I stated before distance is distance. IF the distance to the target is 702 yards, the distance is 702 yards. The True distance is 702 yards. If its at an angle of 90 degrees straight up, the distance is still 702 yards.

We often talk about shooting at angles and there is "effective distance" used sometimes or "Effective dope" aka use the dope for 600 yards if shooting at incline X for 700 yards. I think you would find more help if you could be more descriptive.

 

[Alabama556]

TheotherAndrew got me what I needed above. Thanks for the input.