Ballistics on uphill/downhill shots

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yellowknifedave

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Howdy.

Is there a formula for figuring out bullet rise or drop with uphill/downhill shots? Flatlander like me will be shooting in some hilly areas this fall; probably up to a 60 degree grade up or down from 100 to 200 yards. How should I aim my downhill shots? Uphill shots?

Never have had the chance to shoot at the range on an incline, but shot placement and accuracy are important to me; I want the deer to drop right away, as I have always done on the flat land.

Any educated replies are welcome.

Thanks.

YKD
 
aim lower,...

depending on the incline and distance it will vary, but for all intention purposes, I have found that a rifle with realtively flat trajectory to 300 yrds can be compensated for with about a 3 inch hold under, to about 350 yrd target
 
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Good question, I was also wondering the same thing. Were I live we never get any uphill/downhill shots. I am kinda interested in hearing the answers to this.
 
The important factor is the horizontal distance to the target,not the straight line distance to the target.If you are 300 yards from the target horizontally ,but due to a steep angle you are actually 400 yards to the target in a straight line,aim as you would for a target 300 yards away on flat ground.Range finders measure the straight line distance to the target,but you can calculate the actual horizontal distance using the straight line distance and angle.It's basic geometry using a right triangle.

http://www.snipertools.com/article5.htm

http://en.wikipedia.org/wiki/Rifleman_rule
 
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There is.

D (distance - straight line) multiplied by the cosine of the angle (up of down doesn't matter) of incline/decline equals horizontal distance (the distance of which gravity effects a bullet).

For example:

Distance is 1000m
Angle is 30 degrees (cosine of 30 degrees is .8660)
Therefore the true horizontal distance is 866m.

The greater the angle, the shorter the true horizontal distance will be.

This uses the old high-school principle of right-triangles. You always have one corner of 90 degrees and the opther two angles must also add up to 90 degrees.

To illustrate, you are on the below triangle at A, your target is at B and you know the length of h. You need to solve for b. You use the cosine of the angle at A to solve for b.
288px-


Clear as mud? Where the hell is Hungry...he teaches high school kids!
 
Simply,

Shooting downhill aim a little low,
Shooting uphill aim a little low,

If you suspect 500 or 600 yrd shots and 70 degree inclines, you might want to do some calculating. But minus calculating angles and distances on a hillside when there's a nice elk in front of you, if you are +/- 3 or 4 inches to 300 yrds, just aim 3 inches low if your shot is within 350 yrds
 
Rotaxpower said:
Good question, I was also wondering the same thing. Were I live we never get any uphill/downhill shots. I am kinda interested in hearing the answers to this.
Click to expand...

I have used a fairly quick rule of thumb for sensible uphill/downhill shooting situations.

15 degree : cut 3% off distance and recalc your scope elevation for the new distance (true horizontal distance to target)

30 degree : cut 13% off distance and recalc your scope elevation for the new distance (true horizontal distance to target)

45 degree : cut 30% off distance and recalc your scope elevation for the new distance (true horizontal distance to target)

I did not go or had to use steeper angle calc.

I carry a simple school plastic gizmo to help with inclination calc.

Distances and angle estimation in real life/hunting situation can be misleading.

Have fun.

BB
 
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