Yes it does make  difference ! When shooting a steep downhill you will have to aim lower and when shooting a steep uphill you will have to aim higher. If you have a range finder that is able to tell you the difference in yardage on steep angles it would be a big advantage for you.

Gravity and loss of velocity act on the bullets' travel on a horizontal plane. Doesn't make any difference if the target is 20 degrees up or 20 degrees down, it's the horizontal distance that matters.  Think of a triangle; the straight line distance from gun to target will be greater than the horizontal distance at a point 90 degrees up or down from the target.  If a long way away, compensate point of aim based on the horizontal distance. That's what the latest batch of laser range finders are doing. 

I always heard to aim low on both uphill and downhill shots.  I know that there is a method to figure it out somewhere out there on the web. 

You're right Critter, aim low to compensate for steep angles.  Last I read, with typical hunting calibers the amount to compensate isn't worth worrying about until you get past 150 - 200 yards.

It does make a difference on longer shots

40 deg incline, line of sight is 400yds, your aim shot be 335yds.

the biggest proble is finding the slope(angle) of the slope, lots of pratice

V/R

M.Bird

The ballistic distance is the horizontal distance to the target excluding the vertical rise or drop.  Thus you always aim lower on an angle (up or down) because the horizontal distance is shorter than the line of sight distance.  Rangefinders with inclinometers automatically compensate for this ballistic distance.

like has been said it is the horizontal distance that is of importance. Although it does make a difference i feel it is relatively mute at reasonable hunting ranges. In order to cause any sizable difference in POI at distances under what any of our rifles will shoot point blank anyways you have to get to angles of obscene degrees (above 45 degrees). Get a square and look at what 45 degrees above or below horizontal and try to imagine a place where you hunt that you would be taking a long shot at that angle. 20 degrees is about the steepest I can imagine anywhere other than Mountain goat hunting (I am from Colorado btw). Where I can see a difference is archery from a tall tree stand. A 20 foot high tree stand can make a difference of 2-3 yards at reasonable distances. with a bow 2-3 yards can make a difference but 15 yards at 200 or even 400 yards makes little difference with todays rifles 

thanks for the input.  i have looked it up quit abit after getting a few different response back and from what i gathered is that most of the flat shooting rifles that most of us use should not be a big problem unless one tries to shoot a chipmunck at 400yds at a 45 degree angle.  but what i read on here and searching sites is that if you are making a long distance shot at an increased angle you should aim slightly low. the difference in the yardage is not much when pulling out your calulator and going back to high school days using calculus and trigonometry, which i took but cheated off the validictorian and never learned anything.  maybe thats why i had to read the expanations several times to make heads or tails of it.   anyway thanks for the comments and good luck to all,  seasons are just around the corner.

The big thing is that you need to know the balistics of the round that you are shooting.  That anong with the real distance will help you in any shot that you take.  I love it when a hunter tells me that he held on the top of a elks back and hit him right in the boiler room and that the elk was 600 yards off and that he has his scope sighted in to be dead on a a hundred.  In the real world that bullet that was just shot at an elk will drop real fast once you pass the 200 yard mark so it takes practice to know just how far an animal is and how to aim to make a killing shot. 

I've taken one shot or I should say two at an animal that was really a little too far away.  My problem was that there was just no way to get any closer.  But I had two things working for me.  One was there was no wind what so ever.  The second was that I knew just about everything there was to know about the round that I was shooting.  The first shot hit the elk and turned him around.  My spotter didn't see the hit so I shot again and the elk went down.  Come to find out I had hit him twice and both were killing shots.  Once we got to the elk he couldn't believe that a rifle could shoot that well at that far of a range.  I just told him that it does if you do your home work and put in the time at the range. 

Yeap, aim a bit low for angled shots.

Before season starts, climb into your favorite stand and try shooting at some Coke bottles to find out how much you need to compensate.