Shooting downhill.

tignme

Well-Known Member
A new permission i have is about 12 acres of whin and scrub.
its on a fierce slope and i can only shoot from top of hill just now.
Ive fixed two doe boxs 1 third along from ends.
Ive seen up to 14 Roe in and around area.
at bottom of hill is next doors farm.no permission yet but hes swaying.
Any way i have not a lot of experience shooting downhill, the max distance is 280 mtrs.
before i start on paper downhill at distance is there a guide or chart for downhill shooting.
My experience is mostly over 120 mtrs on levelish ground.
Slope is approximately 1 in 15.
 
Basic trigonometry. Shooting down hill has the exact same effect as shooting uphill, it effectively shortens the range. Gravity works on the horizontal plane only. For practical purposes, a 1/15 slope over 200ish yards is not going to make a lot of difference

I can't draw diagrams on this forum, but picture a right angled triangle. If you were 300 yards above the target, shooting at a target 500m away, your bullet would only drop the same as a 400 yard shot fired on the horizontal.

Probably not a good explanation, google for diagrams.
 
I did start a thread on this subject which was quite popular!

Basically you need to ascertain the horizontal distance to the target because gravity works on the bullet on the horizontal plane.

If you use the uphill or downhill distance to the target then you will shoot above your POA because this distance will be greater than the horizontal distance.

Think of the problem as a right angled triangle with sides A (bottom side or horizontal plane), B (upright side) and C (hypotenuse or hill slope).

If side C is 220m (your distance up or down hill to the target) then side A (the horizontal plane) might be 150m. If you incorrectly use the distance of 220m when calculating bullet drop you will fire over the target. Use the distance of 150m you will be spot on because gravity works on the bullet over the horizontal plane.
 
Also remember you are shooting at a 3 dimensional object so will need to aim a bit higher up the body to ensure a good heart and lung shot when shooting down hill, or vice versa for uphill
 
The way we do I it is you need to work out your cosine this can be done by either fitting a cosine indicator to your rifle or converting an angle in degrees to cosine using a conversion chart. Measuring degrees straightforward it can be eyeballed, measured with a simple device or using hand angles. Once you have found your cosine it's a simple formula

Range x cosine = applied range
eg. 600yards x .82 =492 yards applied range
View attachment 67669 View attachment 67670
 
For a 1 in 15 slope, the difference is negligible.

Assuming that your 1 in 15 is correct, that works out as a 3.8 degree angle. Also, assuming your 280metres is correct (and is a lasered distance from you to the deer) then that is your hypotenuse of your right angled triangle.
From those 2 bits of data, we can work out the horizontal distance to the deer. And it is .... 279 metres.
 
Up here we call 1 in 15 fairly flat ! . I would just aim normal place as sometimes people can over complicate the shot, which usually results in messing the shot up.
 
Basic trigonometry. Shooting down hill has the exact same effect as shooting uphill, it effectively shortens the range. Gravity works on the horizontal plane only. For practical purposes, a 1/15 slope over 200ish yards is not going to make a lot of difference

What CD said.

But...in effect, illogical as it seems, you should on a two dimensional target, aim lower than you would than if you were shooting "on the flat".

But, but, but!

Be aware that an animal has three dimensions so the bullet path through the animal won't be horizontal. Thus the vital part, shooting downhill, will be below the place where your bullet enters the beast.. so you should in fact aim higher than if the animal were horizontal to you.

Hope my little diagram makes it clear? It's a slice of a deer that is looking at you the viewer head on. But the shot taken by a shooter that is side on to the deer.

The black line is a shot on level ground at the appropriate point of aim on the body of the side on to the shooter deer. The red line is a shot fired, side on, from above the deer at that SAME point of aim. The green line is a shot fired, side on, from above the deer at the CORRECT point of aim.

If shooting uphill or at something in a tree or on a ledge on a cliff for example then shoot lower than if on the level.

View attachment 67683

This is even more relevant if shooting from a high seat of course. Click on the image to enlarge. The red bit is the vitals.
 
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As we used to say you will drown of boredom in the class room....


The simple thing to do is go stick up a couple of targets at what range you are happy with, then shoot from your box....
I would make a couple of roe size targets and then you can gauge the size at the distance.

The more effort you put in the more you will get out....


Tim.243
 
On my steepest bit of highland ground, over 380 meters down the hill, the difference between the distance and the adjusted difference is about 15 meters maximum using fancy binoculars!
 
Forget about it.

It won't make a noticeable difference over that range.

Adjust for position of the heart as you would if the seer was facing away or towards, but up or down
 
This is a very good video




This. This guy did an excellent series on practical rifle marksmanship.
Where I shoot we have the possibility of shots up or down to 40 degrees. For hunting I use my calibrated eye ball to determine the angle, for long range target shooting I have an electronic angle meter made for carpentry. (1.5 x 1.5x 1 inches) They make some pocket cards that have a metal wire pendulum. You sight along the card and pinch the wire when it is vertical, reading the angle off the side of the card.

As this video will detail, most people grossly over estimate the angle they are shooting at. A fellow I was shooting with last week swore that the 500 yard gong we'd set on a hill side was at a 40 degree angle. In reality, it was about 12 degrees up-angle, which required still 96-ish percent of full target distance value.~Muir
 
As already posted the slope over that distance is of no real importance at all , be aware of back stop and adjust point of aim on the body to ensure the shot penetrates the vital organs and you don't brisket it. It's not like long range targets, sub MOA. the kill zone on even a small deer gives room for error but better slightly high hit point than a low one.
 
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