Down Hill Shots

[fishhead]

Is there a formula or some method of determining how much to compensate for downhill and uphill shots?

Thanks,

Chuck

[MarinePMI]

Fishhead,

Unless you're shooting ground squirrels at 200yds, at 45 degree angle I wouldn't worry about it. ###I'll look at home in my various books tonight, but I don't think there's much out on the subject. ###On another note, if you know a Physics Major, they'd know the formulas that would calculate the force of gravity, the angle fired and the ballistic coefficient of the round to give you the answer...

[QALHNTR]

<font face="Tahoma">I've read several articles which seem to really stress taking the angle into consideration. ###It mostly applies to long range and severe angles. ###It went something like this. ###You see a huge hog about 375 yards away and almost straight up a hill. ###You know your bullet will hit say 4" low at that distance. ###So you hold a little high to compensate. ### The problem is that given the extreme angle, the force of gravity is only affecting the bullet over a very short distance relative to flat ground. ### Therefore, you bullet acts as if the shot was only 50 yards. ###Your bullet is now above the barrel and you also held high. ###Your bullet sails about 3" over the hog and he runs into my field where I drop him in his tracks :smile-big-blue: ###Supposedly, it works the same way on extreme downhill angles. ###It seems that a slight uphill or downhill shot taken at closer ranges would not be affected enough to worry about. ###It's probably more important to slow your breathing down and take a good shot in that scenario. ###</font>

[rlwright]

The effect of gravity is only concerned with how much time the bullet spends in the air. The bullet will drop with a downward acceleration of 32.2 feet per second per second. So it doesen't matter what angle you shoot at, the bullet will drop the same amount for a given time interval. It only matters how far away the target is and in turn the time it takes to get there. Gravity varies as you get farther from the surface of the earth, but for hunting purposes this is negligible because relativly speaking the bullet is still close to the earth.

[Speckmisser]

Fishhead,

I believe there's a lengthy discussion of this further down in this forum... or possibly under rifles. ###

Up or down angles definitely tend to put your hit above the point of aim, but the difference is usually minimal (with the exception of extreme angles). ###I believe you'd probably find as much of an impact on your close-medium range shooting at sharp angles as you would at longer ranges.

For shots on big game, the difference is probably not worth the brainpower you'd use calculating it. ###But if you're shooting at the 10-ring, or trying to remove the eyes from a ground squirrel, it could be worth the research. ###There is a formula, but the variables are mind-blowing... unless you really like that sort of thing.

On outdoorlife.com, Jim Carmichael has several columns and articles about it (search the archives). ###I imagine the other shooting and marksmanship sites also have discussions, but I don't really frequent them. ###

[Lollypop]

An easy way to address this idea is that one needs to just consider the component of the force of gravity perpendicular to the shooters line of sight with the target. The further the line of sight ###is from the horizontal, the less the effect of gravity on the bullets path IN THE DIRECTION OF THAT COMPONENT. (ie. the COMPONENT of the gravitational force on the bullet's path deflecting it from the line of sight, tends to zero as angle of line of sight is increased from the horizontal).

But as everyone else has mentioned, this is negligable unless the angle is large and distance is far: - then the only compensatione necessary is to aim lower than otherwise.

To determine when to start compensating is best investigated running simple ballistics programs for your particular bullet, muzzle velocity, etc. These are all simple to use and availale from companies like Sierra and others.

BUT for most of us hunting at less than 300 yards with high velocity rounds and lines of sight less than 30 to 45 ###deg from the horiz...I wouldent give it another thought provided you have not set up your point blank range for a 1/2 inch kill zone.

Otherwise, break out your range finder, determine the target elevation, plug the data into your Compaq Ipaq, determine bullet drop for the conditions at the target and fire away...if the Elk is still hanging around waiting for you.

Have careful fun

[songdog]

I've always found it easier to miss the first shot and wait for the deer or elk to run up the opposite hillside to a level even with me, thus negating any compensation needed for an up/down angle shot :wink-yellow:

[fishhead]

Songdog,

That's how I shot my hog.
It was down hill at 60 yards and I missed.
I hit it on the run level at 100 yards.
Trap shooting helps.

[james marquess]

Fishhead...if you know the distance (mil-dot scope, range finder or what ever) mil-dot cards have a gizmo on them were you can hang string with a weight ###and tell the angle
and the distance for the shot. This seems to work on long shots when you have the time.
I can't re member the slope angle but I use this system for a 450 yd shot and it was right on.Kilt that thar pig.

[so cal hunter]

Has anyone ever heard of Mil-Dot Master? i purchased one of these excellent devices for my long range shooting it is basically a printed card with various measurement&#39;s on it such as target size, mil&#39;s, moa,bullet drop. ect. it will give you all the info. you will need for any type of shot. Range calculation&#39;s( wether performed by a mildot ret, laser range finder or other mean&#39;s) are a measurement of the line of sight distance to the target, bullet drop figures are alway&#39;s expressed in the term of diviation from a horizontal traj. the effect of up or down slope increases with the angle of diviation from the horizontal and increasing range. if shooting uphill or downhill the shooter must estamate the angle by which the shot deviates from the horizontal and reduce the estamated range accordingly this "actual horizontal range" will determine the bullet drop. so basically when shooting up or down at severe angles the bullet drop is the same in either case the actual horizontal range will be less then the estamated (line of sight) range wich mean&#39;s the amount of bullet drop will also be less. the web site for mil-dot master is www.mildot.com so cal hunter

[so cal hunter]

Hey Fishhead; i ran down some figures for you here they are at 200 yd. range level ground. you are zeroed. at the same distance but at 30 deg the actual distance will be 175 yds. ti the target at 40 deg. the distance will be 155 yds. at 50 deg the target will be 128 yds. at 60 deg the target will be 100 yds. this is calculated for a 18&#39;&#39; taget at 2.5 mil&#39;s.

[John M.]

As I understand it the only real consideration need be the horizontal distance not the angular distance. If your aiming at an animal uphill and the distance to that animal is 400 yds. but the horizontal distance to a spot dierctly beneath the animal is 350 yds., you figure bullet drop for 350 yds.

[Speckmisser]

John M., that&#39;s dead on.

From the muzzle to the target is the only distance that you should be concerned with, since it is only in that distance that gravity will have an opportunity to affect your bullet. Doesn&#39;t matter if it&#39;s up or downhill.

[doghouse95]

I&#39;ve never taken the time to figure out what the exact compensation was for any particular
angle, up hill or down hill.
I know from a lot of shooting at extended distances that I always hold a little lower for
these shots. The longer the shot, the lower on the target I hold. I shoot with either a
shepherd, or a VariX3 from premiere recticle. When I shoot with the leupold at extended
ranges, I always start with a range finder.
I can&#39;t give you exact numbers. This is just something we practice until we get a, "feel,"
for the proper sight picture.

[so cal hunter]

I think you guy&#39;s need to take a step back a look at this thing again. how are you going to determine the angle to the target? as the angle changes so does the distance. the steeper the angle the shorter the distance and just oppisite for lesser angle shot&#39;s.a miss cal. of angle of only 10 deg. will put you off by 20 yds. you might have seen the figures i put up a few posting&#39;s back. i have talked to several sniper/ sharpshooter&#39;s and this angle thing is not just a shot in the dark.it is a very criticle part of shooting/ hunting. i am not a know it all by any mean&#39;s but have plenty of reference book&#39;s if you would like more info. so cal hunter

[so cal hunter]

Hey i just found my angle fireing chatr and will put the basic formula in for those who care for it. the formula is (slope range x cosine of slope angle =horizontal range. so if you have a slope range of 200 yds and the angle is 45 deg you would multiply 200 x .70 to get the true distance which would be 140 yds.like a few of the guy&#39;s said this is a complicated formula for hunting use. well here is the cosine #&#39;s for the basic angles. 30 deg.=.87 cosine,35 deg =.82 ,40 deg =.77 45 deg =.70, 50 deg = .64, 55 deg = .57, 60 deg = .50, 65 deg = .42, 70 deg = .34 ,75 deg = .26, 80 deg = .17, 85 deg = .09, 90 deg = .00 i simple way to figure the angle is with a 98 cent protractor a short piece if string and a paper clip tie the paper clip to the string and the string to the protractor on the flat side oppisite the the 90 deg mark and you have a angle meter . to use this you will look at the target from the flat side toward&#39;s the 90 deg mark and 0 deg at the bottom the string will hang down at the angle of the target this is for up hill shot&#39;s. for down hill shot&#39;s you will look from the 90 deg mark on the protractor toward&#39;s the flat side of the prot. where the string is attached the paper clip will hang down to the correct angle. take the angle X by the correct cosine and there you have the correct distance. i hope this does&#39;nt confuse anyone is it does i can fax a copy of the info and the drawing of the angle meter. so cal hunter

[John M.]

I don&#39;t realy know how accurate you have to be with thing. I suppose if your shooting squirrels at 400 yards or taking long shots on large game at 700 + yards you might need to be really accurate in determining the angle from horizontal.

There is a tool that geologists use to determine these angles, I beleive it&#39;s a brunton compass, if not there is also inclinometers. This in conjunction with a good range finder, you&#39;ll have your data.

If your hunting at extended ranges, you might have time to use it.

Now here is the kicker. If you need to shoot that accurately you&#39;ll need to also be doing alot of ballistics research with you firearm and the bullet you plan to use as each bullet/cartridge/gun will give you different ballistic coefficients. There is also weather conditions, which have a fantastic impact on bullet flight characteristics.

What is it that you are actually planning to do? There is probably a practical solution to you particular shooting needs.

[Speckmisser]

I made this dumb little graphic to illustrate the idea.

http://www.elwing.com/hunting/jhpimages/uphillshot.gif

In this image, the "Range affected by gravity" is the distance you have to consider in order to calculate bullet drop. You can see here that the actual range affected by gravity is significantly shorter than the line of fire (the distance the bullet will actually travel).

The image shows a very steep hill, by the way, which is probably the only time most gun hunters will ever have to be concerned with this calculation. A deer on a 600 foot cliff will be a tricky proposition. A deer on a hill at 15 degrees and 150-200 yards away is much less of a challenge. Bowhunters, for whom a five yard miscalculation can be the difference between success and failure have a bit more to worry about. We can deal with bowhunters in a different forum, though. http://www.jesseshunting.com/forums/style_emoticons/<#EMO_DIR#>/smiley-cool-shades-down.gif

SoCal Hunter is absolutely right, of course. In order to calculate that Range Affected by Gravity, you have to fall back to the old high school geometry class and recall how to calculate the sides of an angle.

Since most hunting areas aren&#39;t marked out in yardages, and ridges don&#39;t have the angles of inclination/declination marked on them, though, this could be a little hard to do. Few of us will have the opportunity in a hunting situation to pull out the paperclip pendulum and protractor, and I know that there is no transit or Brunton compass in my fanny pack. How about yours? Heck, I don&#39;t even own a range finder.

What to do?

For rifle hunters, there is one key thing that makes sense. Keep your shots within a reasonable range. If you&#39;re not trying 500+ yard shots, then most angled shots aren&#39;t gonna vary enough to matter. If you miscalculate your range by, say, 20-30 yards at 200...or even 250 yards, how much is this going to vary your point of impact. With my -06, I&#39;m confident aiming point on, high shoulder, at any range from 0 to 250 yards and still making vitals on a deer-sized critter (I zero at 100). Bullet drop is even less of a problem if that 250 yard shot is uphill or downhill, so I&#39;m perfectly safe holding dead-on. Make sense? (By the way, when I&#39;m definitely inside of 100 yards, I&#39;m probably not shooting high shoulder, but looking for something with less meat damage... I&#39;ve heard the debates, but I still like a good neck shot when the conditions are right.)

I&#39;d say most of us have no business shooting game at ranges where a 20 yard miscalculation will be the difference between a hit and a miss...or worse, a crippled animal. You&#39;re already throwing the dice at that point. I&#39;ll add that, for most modern rifles, the distances at which you&#39;ll start to see that much drop are pretty extreme, so you&#39;ve got lots of leeway.

Varmint hunters are excluded from this, by the way, since I know long range shots for varmints are part of the game. This is also different if I am a sniper trying to take out an armed bad guy with an instant kill, so I&#39;m not discounting the feedback So Cal has received from his sniper friends. A brain shot through the window of a car at 200 yards is a different story altogether than trying to hit vitals on big game (that can&#39;t shoot back, by the way).

Angle of the shot is definitely a factor, and should always be considered. But I think most of us, for hunting purposes, are well enough served by simply being aware of how this works, and possibly making general allowances when we choose to shoot.

I&#39;ll close by opening up another can of worms... I think that, besides the ballistics of your chosen weapon, the only other condition you should be accounting for when you take aim is wind. A stiff breeze (15mph) can have incredible effects on bullet flight at ranges as short as 100-200 yards (as much as three or four feet!).

Now if you wanna wrestle with an octopus, figure out how to deal with that one!

[so cal hunter]

Hello again and good day; Hey Speckmisser all of this is true i guess this topic was a sticky one. like you said a close shot of 100-200 yds you really should not have to worry about hitting the spot with a rifle. i am a bowhinter and like you said before. a misjudged range of only a few yds. is a clear miss or at worst a very bad hit. i know this all to well. it has happened to myself a few times and this is why i have been studying this and other factor&#39;s that effect projectiles be it bullet&#39;s or arrow&#39;s i picked up a really great book called, (the police and military sniper) Mike .r. Lau is the author. this book is very informative! i have been going to the gun range lately and watching the bench rest shooter&#39;s practice and asking question&#39;s . since i am of no threat to them (not a competitor) they are pretty good about talking with me about different thing&#39;s in regard&#39;s to shooting. and reloading. there is a wed site called ( point blank.com) it is FREE and really a good balistic&#39;s program. check it out sometime. well it seem&#39;s that i could go on for some time but i will go for now . you all take care and good luck hunting/ shooting in the coming day&#39;s. P.S. hey speckmisser i like the drawing i wish i had the ability to do that. so cal hunter.

[Speckmisser]

Just a quick one...

SoCal, I&#39;m new to archery, just started this year but I know exactly what you mean. Figured I&#39;d leave that discussion to the archery board, though, and let someone there explain how to compensate. I know the theory works the same way, but like you said (and I&#39;ve learned) a couple of yards can make a really big difference. I shoot traditional, and the difference between 20 and 25 yards is shocking. Nice thing about trad, though, is I don&#39;t have to figure which pin to use... just "picture" the arrow&#39;s flight and allow for it. Cool stuff, and I&#39;m totally hooked.

Oh yeah, back to the topic... I&#39;ve checked out pointblank software. Pretty cool stuff. Really handy to get a tangible idea of what your bullet will be doing at various ranges.

[DB Bill]

Wow! By this time anything you wanted to shoot as walked off and died of old age. HERE&#39;S THE RULE OF THUMB....estimate the line-of-sight range and then hold a "little low"....how much? You need to get out and practice to find out. Get your rump off the shooting bench and out into the field.

[so cal hunter]

Hey Speckmisser; so you also shot archery? the trad thing just did not fly with me i did it for a few year&#39;s got tired if missing at 50 yds, so went to a mathew&#39;s that shoot&#39;s a blistering 320 fps. at 72 lbs. with the carbon shaft&#39;s this cut&#39;s down on the miss judgement but i use a laser range finder and sometimes my tree stand. well back to the problem at hand. it seem&#39;s to be how much to hold under when shooting up or down hill. several people have stated there is a need ofr practice i cannot agree more so find a place that has some various degree&#39;s of slope and start shooting and see just where YOUR gun shoot&#39;s at the various angles. well so much for this topic how about going to wind and mirage????? OH my did i open another can of worm&#39;s/ problem&#39;s. well it&#39;s fun to play with because when you are out hunting and a problem like these arise what are YOU going to do!!! talk to ya later so cal hunter p.s. hey i was scouting up around monrovia calif, foothill&#39;s and saw 20 deer in the front of this house several doe&#39;s/fawn&#39;s , a 4x4, a 3x3 and 1 spike all within 10 ft. of my car my wifr thought i was going to have a heart attack!!!! oh i wish i lived in monrovia for bow season!!!