shooting uphill


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bradm
March 28, 2008, 04:49 PM
When shooting from the bottom of the hill at animals at the top of the hill, do you hold low, high, or right where your scope shows?

A guide on a recent hunt (my first ever) said I need to hold high (after my shot hit about 6" low at 150 yds, scope zeroed at 100 yds), while the other hunters said to hold where the scope shows.

I really want to do this right on my next hunt, since my first shot, although it nearly took off a front leg, did not kill the hog or stop him from running at full speed. I hated feeling that the animal suffered due to my ignorance.

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Hkmp5sd
March 28, 2008, 05:07 PM
For both uphill and downhill shots, you need to aim LOW to compensate for the angle.

Harve Curry
March 28, 2008, 05:45 PM
bradm ,
To add to what Hkmp5sd correctly wrote.
Gravity working on the trajectory of the bullet is the flat horizontal distance across the earth.
On uphill or down hill shots the real distance (as far as trajectory is concerned) will be shorter.
So you have to estimate that when you make a up or down hill shot. Figure the angle, 45 degrees or whatever, and deduct that from what the laser range finder reads.
I don't know the formula, I just guesstimate.

351 WINCHESTER
March 28, 2008, 07:44 PM
That's correct. You hold low otherwise you will most likely shoot over your quarry. I read that years ago in a gun magazine before we had computers.

K3
March 28, 2008, 10:13 PM
Sometimes I keep a little notebook handy with some trig problems worked out. I use a laser to get the linear distance to target and generally I know the elevation distances where I hunt. From the canyon rim to the flats below, the vertical distance is usually ~200' or about 70 yards.

I wish I could eyeball distance better, but I was not blessed with that ability.

eliphalet
March 28, 2008, 11:43 PM
At 150 yards it should make no noticeable difference, the bullet will hit where you aim. At least the several deer I have killed up or down have, some extremely steep well in excess of 45 degrees. My own experience is all I can draw on and not what some one said or wrote.

Edit: Have shot ground squirrels on or about 100 yards up and down too at approximately 45 degrees with a .223 and was aiming right on, so aiming on target worked for me on small critters too.

Long distances will change the trajectory and point of impact at steep angles, but at 150 yards it is not far enough to tell in the field, in your typical hunting environment IMHO.

mewachee
March 29, 2008, 03:06 AM
I learned this my first year rifle hunting for elk. It can make a big difference. When you shoot a sighted in rifle the bullet generally rises about the sight plain, then comes down again. Here is where the problem is. Imagine shoot with the barrel in line with gravity. Of course, with no other force acting on the bullet, it would travel straight up until gravity would stop it, then it would fall straight down. I don't know the calculus, but at let's say 45 degrees up, gravity is not acting relatively at a 90 degree angle to the bullet, but at a 45 degree angle. This increases the gravitational pull on the forward motion of the bullet, but decreases the pull that is pulling the bullet out of it's trajectory (I guess by half). Down Hill shooting is similar, because of the 2nd influence just stated.

I missed a cow elk my first year shooting at 400 yards, at about 40 degrees up. My assumption was that shooting up I would have to at least use my normal hold for that distance or higher (idiot, a responsible hunter should know the ballistics of his weapon, in any hunting situation he might be in). I shot at her lying down, then broadside and then quartering away. All, three shots high.

I have since gone back to the same mountain, and shot the same shot in to paper; I should have held 18 in. low. There are ballistic programs that you can put in the shot angles, then you can use the results on a cheat sheet.

dagger dog
March 29, 2008, 09:28 AM
A great book on this and other ballistic related info is
UNDERSTANDING FIREARM BALLISTICS by Robert A. Rinker
ISBN 0-9645598-4-6 published by Mulberry House Publishing PO Box 2180 Apache Junction AZ 85217,USA
1-888-738-1567

This book is written in lay terms also for you number crunchers a lot of formulas pertaining to the subject. It will make a lot of misunderstood facts easy .

I can't go to say enough about this book I picked it up at a show and it has sure opened my eyes!

mewachee
March 29, 2008, 12:10 PM
thanks for the reference.

ShunZu
March 29, 2008, 12:44 PM
For both uphill and downhill shots, you need to aim LOW to compensate for the angle.

+1. Although it defies logic, low for both angles. And the steeper the angle, increase your aim (lower) accordingly.

Titan6
March 29, 2008, 02:08 PM
When shooting from the bottom of the hill at animals at the top of the hill, do you hold low, high, or right where your scope shows?

Other than hunting in Colorado I have rarely been lucky enough to have the option of shooting at a target on top of a hill. Normally that is a rule violation.


For both uphill and downhill shots, you need to aim LOW to compensate for the angle.

+1. Although it defies logic, low for both angles. And the steeper the angle, increase your aim (lower) accordingly.

This is quite true.

dagger dog
March 29, 2008, 02:22 PM
Squirrel hunters are faced with this problem from the get go. Thats why I miss so many!!!!!!!!!!!

highorder
March 29, 2008, 03:25 PM
Although it defies logic, low for both angles. And the steeper the angle, increase your aim (lower) accordingly.

um, its quite logical. as others have posted, the actual distance to target is not affected by the same gravitational pull of a shot that is taken over level ground.

Sometimes people say that something is "illogical" not understanding what logic is... perhaps you just misspoke. :)

Vern Humphrey
March 29, 2008, 05:03 PM
The difference in hold due to slope is often highly exaggerated. Going to Ballistic Explorer, I plugged in a .30-06, 180 grain bullet, 2800 fps. Zeroed range was 225 yards, and compared trajectories for 0 degrees slope with 45 degrees slope.

The difference at 300 yards was 6 inches drop at 300 yards for the 45 degree shot, versus 4 inches for 0 degrees. At 300 yards, that's a piddling difference -- probably well within the margin of error for the rifle and shooter.

On the other hand, a real problem with shooting up and downslope is foreshortning -- it's often difficult to visualize where the critter's vitals are, so you will get a center hit, but miss the vitals when shooting steeply up- or downhill.

dagger dog
March 29, 2008, 05:19 PM
Vern,

Add in buck fever, physical exhaustion, pressure to get the shot in time plus equipment problems etc.
and that margin gets a lot wider.!

The deer hunter in the tree stand has a foreshortning problem for sure and the bow hunter has it in spades, as he trys to get that arrow through BOTH lungs.

Vern Humphrey
March 29, 2008, 05:27 PM
The deer hunter in the tree stand has a foreshortning problem for sure and the bow hunter has it in spades, as he trys to get that arrow through BOTH lungs.
And they have those problems at very short ranges -- where the gravitational effect of shooting up- or down-hill would so small as to be unmeasurable.

mewachee
March 29, 2008, 07:58 PM
Vern, "unmeasurable" just isn't right. A five hundred yard shot is only the beginning of a long range shot here in the west, at least for a lot of us. Bump your distance out to 400 or 450 and you will see the difference of good shot and a miss.

If you look at the distances between the first time the bullet pass through the sight plain and the second when it comes down, there is a considerable difference. By pushing the sighting out to 250 yards and looking at data only at 300 yards, you don't get data representative to other distances.

I would call it measurable and any ethical hunter would take this into consideration.

Vern Humphrey
March 29, 2008, 08:03 PM
At 350 yards, the difference is only 4 inches -- and beyond 350 yards, I would think long and hard about shooting.

Let me point out also that the angle is 45 degrees -- it ain't often you get a shot at that steep an angle. Change the angle to 30 degrees -- still very steep, and the difference at 400 yards is only about 2 1/2 inches.

Sergeant Sabre
March 29, 2008, 08:24 PM
I am a firm believer that "slope dope", as it is called, is absolutely negligible in hunting situations. Meaning, not a factor at all to the hunting rifleman, hand gunner, or bow hunter.

However, our toy manufacturers are starting to cash in on the mysterious phenomenon of a bullet or arrow "floating" when launched at an uphill or downhill angle. Leupold now has range finders that will calculate the angle and adjust from linear range to true range. It's just a gimmick that their advertising people will try to exploit, but some hunters will buy it.

I will re-iterate: "Slope dope" is not a factor to the hunter.

mewachee
March 29, 2008, 08:24 PM
I use a leupold RX-IV range finder that tells me my angle of shot and hold over. When hunting mule deer and elk, I have to climb a 1000 feet before the sun even rises. Other than shooting hill to hill, I have an up or down shot. Since I have used this range finder, I have not missed. I can trust it, because I have shot with it.

Again, I don't believe one can put a distance on what is ethical and not. I do however think if you can't shoot inside 8in at 100 yards you should take the shot. If you can shoot a balloon at 600 yards with your rifle confidently, then I say go for it.

mewachee
March 29, 2008, 08:26 PM
if you shoot paper in these situations, you will not think it is a gimmick.

Vern Humphrey
March 29, 2008, 08:30 PM
Where do you shoot paper at steep angles? And without sighting shots?

mewachee
March 29, 2008, 09:10 PM
When we scout, we bring balloons with us. We hunt with the goats sometimes. That is where we find the big mules.

Zak Smith
March 29, 2008, 10:45 PM
I've shot extensively out here in the West and it is almost unheard of to need to make correction for angle of fire because to apply a large angle over a long distance shot requires a huge amount of vertical elevation vs. the target (or vice versa).

However, it is not quite correct to use the "level distance". This page explains why and is pretty much the last word

http://www.exteriorballistics.com/ebexplained/article1.html

eliphalet
March 29, 2008, 10:46 PM
Deleted, Above link is sufficient.

mewachee
March 30, 2008, 01:00 AM
Here is a great explaination and a graphic to describe real world results.

http://www.wildsheep.org/magazines/article_uphill_shooting.htm

http://www.wildsheep.org/magazines/images/articles/30_cal_180_partition_2900_fps.GIF

45crittergitter
April 10, 2008, 09:25 PM
Just to be painfully technical, the horizontal distance is irrelevant to the discussion. If you are reading for entertainment, you may want to stop here.

Please bear with me as I explain without the benefit of the necessary diagrams and way too much time elapsed since high school physics and engineering school.

The major error made was stating that the horizontal distance to the target affects the bullet’s drop. In fact, the horizontal distance is irrelevant. For our purposes, keeping miscellaneous variables such as atmospheric conditions, etc. equal, there is only one force causing bullets to drop – gravity. The only other variable in amount of drop is the time that gravity has to act upon the bullet in flight, i.e., time of flight (TOF). That is because gravity is a vector, acting vertically downward with an acceleration of about 32.2 feet per second per second.

Here is an example. Suppose a pair of shots, both equal distances from the muzzle, say 100 yards. The first is a perfectly horizontal shot. The second is at the mathematically convenient angle of 45 degrees upward (could be downward as well) from horizontal. The horizontal distance of the second shot is less than the first, measuring only 70.7 yards, but this is irrelevant.

Now here is where one must grasp the physics. Both shots are 100 yard shots – the first is a horizontal 100 yards, and the second is 100 yards at an angle of 45 degrees, but still 100 yards from muzzle to target. Since both bullets travel 100 yards at the same average velocity, the times of flight of both shots are equal. Since the TOF are equal for both shots, gravity has an equal time to act upon both bullets, meaning the drop must be the same, right?

Wrong. Bear with me.

While it is true that gravity has the same time to act upon both bullets, the acceleration of gravity does not act equally on them relevant to the direction of drop. Remember, gravity is a vector. In this example, the bullet is a vector also. Vectors have both a magnitude (in the case of gravity, an acceleration of 32 fps/s) and a direction (vertically downward). Vector mechanics involves both the angles and the magnitudes of the involved vectors.

Now back to the horizontal bullet fired in shot one. By definition, horizontal is perpendicular to gravity. Therefore, gravity acts in a downward direction that happens to be perpendicular to the original path of this particular bullet. Therefore, the drop of the bullet is related directly to the TOF and the effect of the full magnitude of gravity (32 fps/s) because gravity in this case acts in exactly the same direction as drop. Simple concept; everybody understands this.

For the bullet fired in shot two it gets more complicated. You see that bullet has a vector direction of 45 degrees to horizontal, and to vertical. While gravity still acts vertically upon the bullet, the bullet is not traveling horizontally or perpendicular to gravity, so gravity no longer acts perpendicularly to the original path of the bullet, but at the 45 degree angle. (This is easier with a diagram.) In other words, gravity pulls the bullet vertically downward, but vertically downward in this case is not the same as drop. Drop, as I understand the definition, is the amount the bullet falls perpendicularly (but not necessarily vertically) away from the line of the original path (barrel). Since the barrel in this case is not horizontal, drop is not vertical.

Now let’s do the math. Picture shot two, upward at an angle of 45 degrees from horizontal, with a muzzle-to-target distance of 100 yards.
Gravity is acting at an angle of 45 degrees from the path of the bullet, rather than perpendicular to it. The component of gravity that is acting in the direction of drop, or perpendicular to the path of the bullet, is described by the equation: (Gravity) x (sine 45 degrees). You will notice that due to the angle this amount is only 0.707 times the horizontal shot’s gravity effect, or about 23 fps/s. The other component of gravity is acting perpendicularly to the first. It acts exactly parallel, but opposite (for an uphill shot) in direction to the path of the bullet and the magnitude is described by the equation: (Gravity) x (cosine 45 degrees). This component can be legitimately ignored as insignificant relative to the velocity and TOF of the bullet.

Just for fun, let’s consider a third shot. Vertical. Up or down, I don’t care. There is zero drop – the bullet stays on its original path with no drop from gravity, because all of gravity is acting exactly parallel to the path of the bullet, and not at any angle to pull the bullet off that path.

In summary, the drop depends upon TOF and angle of bullet path from vertical (gravity). For two equidistant shots with the same load, the TOF are equal, leaving only the different angles to determine the difference in drop.

I hope this has clarified rather than confused. :)

Sergeant Sabre
April 11, 2008, 05:43 PM
The horizontal distance of the second shot is less than the first, measuring only 70.7 yards, but this is irrelevant.

Hmmm...

You will notice that due to the angle this amount is only 0.707 times the horizontal shot€™s gravity effect,

100 * 0.707 = 70.7. So, couldn't we just consider the drop on the second shot the same as a 70.7yd horizontal shot?

627PCFan
April 11, 2008, 09:32 PM
Uh hunters saftey 101? No shooting rifles uphill??

koja48
April 11, 2008, 10:32 PM
I regularly shoot at these ranges and beyond accurately AT PAPER! When it comes to harvesting a deer or an elk, get closer . . . it's commonly referred-to as "hunting," not "shooting & hoping." Each of us as hunters DO have an obligation to: a) ensure a good hit, and b) effect a clean kill. Other posters are spot-on . . . at acceptable shooting distances in hunting situations, uphill/downhill factor isn't a huge consideration on deer/elk-size quarry. However, if you are proficient at consistently placing your rounds at extreme ranges, uphill, downhill, on the flat . . . I acknowledge & respect both your trigger-time, dedication, & your ability. If you lack these characteristics, don't attempt the shot. A high-powered rifle & primo optics ARE NOT acceptable substitutes for patience, stalking ability, or ethical hunting practices. If you can't get closer to your efficient accuracy zone, pass-up the shot. That being said, gravity & the law of physics says that uphill/downhill requires a lower POA to ensure "pin-point" accuracy. And I live "in the west."

Art Eatman
April 11, 2008, 10:45 PM
As Vern pointed out, you won't notice anything of importance until you get on toward 45 degrees. For 30 degrees or less, forget worrying about the angle.

Art

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