shooting uphill or downhill

[George]

In another thread Artificer said, “Oh, don’t forget that when aiming EITHER uphill or downhill, one has to aim BELOW the normal target area or you will shoot too high. Best to get some practice in on this as well to see how much you have hold below when doing such shooting. One hunter in our club was up in a Tree Stand and did not realize this. The Buck he shot at was only 30 yards from his tree, but he missed with three shots.” Don’t want to hijack shootgunner87's thread, so thought I’d start a new one.

What Artificer said about always hitting high when shooting up or down at a steep angle is perfectly true, for all projectiles from arrows to smokeless sniper rifles. it is important, though, for us to understand the degree to which that causes us problems. The effect is worse when the angle is steep, the bullet is slow or the distance is long. It’s not very great at our normal hunting distances. Consider the hunter above, shooting at 30 yards. How high was he in the tree? I’d guess between 12 and 20 feet. Assuming a high stand, lets call it 21 feet, 7 yards. If we plot out the angle by making a drawing to scale and measuring the angle, it comes out very close to 15 degrees. The first Lyman handbook has an excellent discussion about this problem, and gives us some useful data. That shows that at an incline angle of ± 15°, shooting a conical at 1400 fps at 50 yards, the error is only .08”. Even at an incline angle of ± 60° the error is only 1.19”.

So, that shooter didn’t miss his deer 3 times because of the incline problem. It takes special circumstances to make the incline angle error a significant factor in our hunting, and most of us will never experience that situation.

Spence

 

[wayne terry]

Cool, :thumbsup: :hatsoff:

 

[longcruise]

It takes special circumstances to make the incline angle error a significant factor in our hunting, and most of us will never experience that situation.

That's true. The angle means little at short range. One way to calculate this is to treat the range as though it is the base of the triangle. IOW, shooting down at 45 deg at a true distance of 100 yards equates to a 50 yard shot in terms of POI. Even shooting down at 90 degrees from a tree stand 30 feet up is going to be inconsequential with an ML gun. For bow hunters this is much more critical

 

[Artificer]

I would still strongly suggest one try to do some uphill/downhill shooting to see just how much it affects the strike of the bullet/shot with their gun, no matter what the book says.

This because other factors do come into play in hunting like standing offhand and not at a bench, jerking the trigger, heavy breathing, an accelerated pulse, not getting good sight alignment, etc., etc.

The more a person actually shoots their gun in different shooting positions and at different ranges, the more sure they are going to hit the target when it counts.

Gus

 

[BrownBear]

The angle means little at short range. One way to calculate this is to treat the range as though it is the base of the triangle. IOW, shooting down at 45 deg at a true distance of 100 yards equates to a 50 yard shot in terms of POI. Even shooting down at 90 degrees from a tree stand 30 feet up is going to be inconsequential with an ML gun. For bow hunters this is much more critical

Yup. I knew all that, but held over a little and missed the one and only muzzleloader shot I've ever taken at a deer past 100.... It was lasered at 115, and from lots of range shooting I knew that I needed to hold a little over 1' high with my gun sighted in at 75 yards.

Got a good rest, sights steady as a bench rest, and squeezed off the shot. Got to see the ball hit about exactly where I aimed on the dirt bank behind the buck.

Then it kinda all sank in. The buck might have been 115 away on line of sight, but with the steep downhill angle (coincidentally on the order of 45 degrees) the horizontal distance was only on the order of 50-70 yards. Hit right zackly where I aimed!!!! :rotf:

There's so much balderdash written about this stuff that my bud and I went back out to the same spot with paper targets and did a bunch of shooting. We were hitting right on the money, even if the laser said 115 and the guns were only sighted in at 75.

Less confusing to me to think in terms of when it's time to ignore hold over. And of course, to leave the long range shooting to guys who actually know what they're doing! :rotf:

 

[George]

There are many reasons shooting up or down at steep angles can be tough which don't have anything to do with this type of "incline angle error." I believe they usually involve the shooters, not the guns, so the more practice we get the better the results. I have more confidence in the math than in us as shooters, but that's just me. :haha:

Spence

 

[Artificer]

BTW, Spence, that deer only stood still until the first shot rang out and then high tailed it off immediately afterwards. We haven't figured out how to get deer to stand still after the first shot in Virginia, either. :rotf:

Gus

 

[George]

The buck might have been 115 away on line of sight, but with the steep downhill angle (coincidentally on the order of 45 degrees) the horizontal distance was only on the order of 50-70 yards.

And marmotslayer said:

One way to calculate this is to treat the range as though it is the base of the triangle. IOW, shooting down at 45 deg at a true distance of 100 yards equates to a 50 yard shot in terms of POI.

I think you'll find that the ball actually traveles the full distance, along the hypotenuse of the triangle. That would mean the time of flight was the same as normal, so the drop would be, too, which means the trajectory would be, of course. I suspect something else was involved in the miss.

Coriolus force is a perennial fvorite. :haha: :haha:

Spence

 

[longcruise]

think you'll find that the ball actually traveles the full distance, along the hypotenuse of the triangle. That would mean the time of flight was the same as normal, so the drop would be, too, which means the trajectory would be, of course. I suspect something else was involved in the miss.

I think it has less to do with distance and time of flight and more to do with how gravity is applied to the projectile. If the shot is fired straight away, the full force of gravity is pulling it down and out of it's trajectory. If the shot is fired straight down or straight up gravity is still acting equally on the ball but is not pulling it down out of it's trajectory.


so, if we use a "outer space" situation, a ball fired in any direction in the absence of gravity is not going to have a curved trajectory. It is going to continue on a straight line that matches the bore. Meanwhile the sights are set to accomadate the trajectory in such a way that with our ML guns the ball will typically rise up through the line of sight around 25 or 30 yards from the muzzle and then fall back through the line of sight somewhere around 75 to 110 yards (this all depends on load, etc.). So, our ball shot in space will cross the line of sight one time and from that point on the line of sight and the line of the path the ball takes will grow ever farther apart.

This same effect is applied if one shoots straight up or down back here on earth. The ball is going to cross the line of sight at one point and is not going to fall back throught the trajectory because the trajectory is no longer curved. This is not a perfect analogy, but it does apply within the reasonable range limits of our firearms both ml and modern.

So, if we go from having a normal trajectory that will match our sight in on a straight and level shot to a complete lack of curved trajectory when fired at 90 degrees, then the shot fired up or down is going to shoot "high" relative to our sight in expectations. Shots fired between level and straight up or down are going to have variations in trajectory based on the degree of that angle.

The less velocity the projectile has, the more this effect is going to be evident.

 

[BrownBear]

I think you'll find that the ball actually traveles the full distance, along the hypotenuse of the triangle. That would mean the time of flight was the same as normal, so the drop would be, too, which means the trajectory would be, of course. I suspect something else was involved in the miss.

Only thing to do is test your hypothesis with some careful shooting of your own.

That's what we did, and the paper spoke for itself.

 

[hoochiepapa]

I agree. My buddy and I got in a pretty heated argument about this. So we loaded up our hunting rifles and went to Iron mountain which is a very steep mountain bisected by an old mining road. We set up on the road, and picked out quartz rocks as targets. We both hit everything we aimed at, no matter up or down. He won the argument.

 

[Vaino]

Have shot 100s of squirrels in trees at all sorts of angles and held the same as when shooting on the ground. Most of these squirrels were head hits which is a small target.....longer distances surely would make a difference......Fred

 

[bender20]

Spence is absolutely correct especially at muzzleloder distances. If you start doing the math you'll quickly realize that your human error is going to be far worse than not calculating the angle and distance correctly. I haven't played around with muzzleloders enough but I kno with my center fire guns I sight in for mbr and most certainly under 150 I just hold where I want to hit. 98 times out of 100 you'll be within 2 or 3 inches of your intended shot place (assuming you do your part). I think people tend to over complicate this. Archers run into this problem more due to slower projectile speed most bows only shoot 300 fps or so. Drastically less then the 1400 or 1500 fps a muzzleloder is pushing its projectile.

 

[mooman76]

When I was practicing archery for hunting I was told the same. There is some difference but I think there is more of a physiological thing that will make you miss because you think you need to off set it more than needed.

 

[Dewey]

In terms of archery, here is Jimmy Blackmon's views on this subject.
https://www.youtube.com/watch?v=huk5lsIu1_U

Maybe something similar in muzzleloading/aiming ???

 

[longcruise]

You are right on, Fred. If your ball path and Line of sight intersect around the 20 to 30 yard mark, the angle of the shot at "squirrel" range is irrelevant.

Another thing that comes into play is the height of the sight above the center of the bore. Not a big deal with our low iron sights, but significant for modern equipment. Especially for the necessarily high mounts needed for the large bells on the high magnification Scopes.

For archer's it becomes critical when shooting at steep Angles. Especially when shooting trad equipment.

I don't Hunt from elevated stands any more, but when I did, I ignored the angle of the shot with ML guns. Just as Fred is able to do when he is popping squirrels. The closer the animal is to the base of your elevated stand, the shorter the range and the less effect there will be on your POA/POI. At any reasonable stand elevation, the longer the shot, the less the angle and the less the effect.

If you are taking a steep angled shot at the longer ranges like Brown Bear described it can become a factor.

 

[robinsroost]

Y'all are making my head hurt just trying to figure it all out. I have hunted out of trees and I have shot up into trees and I have hunted out West at steep angles. I was taught, and I agree, to aim where you want the bullet to hit, regardless of the angle, at least for your first shot. If you do your part, without trying to overthink it, you will most often be successful........Robin :hmm:

 

[ohio ramrod]

Most people who talk about shooting high or low are thinking about shooting bows from a tree stand. Shooting toward the center of the earth vs shooting at a right angle to the center. Not shooting a gun (much higher velocity equals shorter time and therefore drop) rather than a twenty or even thirty degree incline . As stated, there is a difference but very small. :idunno:

 

[wpjson]

My range at my cabin is uphill a bit, so I contacted a physics teacher and asked her about the affect of gravity on the ball. If you fire uphill the ball requires more energy to overcome gravity. That will slow the ball down and make it shoot lower. If you are firing downhill the opposite occurs. The force of gravity increases the relative speed and uses less energy. The ball will maintain a higher speed for a greater distance, you shoot a bit higher. Then she added the kicker "The impact of gravity on shooting uphill or downhill is so minor you would be best to forget about it unless you are firing at an elk 10 miles away. Then it might make a difference of an inch or so." :hatsoff:

 

[George]

The effect of gravity on the speed of the bullet is not directly the cause of the "incline angle error" which makes you shoot high both uphill and downhill. It's more a problem of geometry, the direction of gravity in relation to the line of sight and the path of the bullet. This is not something new, it has been known about and understood for a long time.

The error is not a problem for us at ordinary hunting ranges, but can be quite great as the distance and angle increase. Here's a chart from the first Lyman Black Powder handbook that shows it well.



Spence