Question for you Guys (& Gals out there)... shooting this weekend with .223 Contender single shot out at 150 yards. Amazed and somewhat baffled at shooting 8 to 10 inches HIGH at this range from maybe a 25 foot high burm at one end of a pit. Shooting at silhouette targets maybe 1 1/2 foot high the impact was all along the top, and over where we could see bullets impacting. Also had 4 milk jugs out that range, and clean missed all of them with the 55 gr. jhp ammo I was shooting. Does anyone know if these will 'float' somehow ??? I was expecting even with a headwind or crosswind that the impact from point of aim would only be off one to two inches in either direction. How is this possible? Also: 21" tapered barrel, shooting rested, 3 x 9 scope zeroed at 75 to 100 yds. Thanks for your ideas on this.

The bullets always strike higher on the target when aiming at uphill or downhill shots. You have to practice at varying distances and varying degrees of loft or depression to know exactly where your particular bullet is going to impact at these angles.

Learned this many years ago in Wyoming while shooting across canyons (big washes) at deer and antelope. Forgot the principle one time in Colorado shooting at a downhill bull elk - held just behind the shoulder joint and watched a patch of snow fall off an overhanging fir branch just over it's back. Things like that tend to stay in your memory bank forever!

The bullets always strike higher on the target when aiming at uphill or downhill shots. You have to practice at varying distances and varying degrees of loft or depression to know exactly where your particular bullet is going to impact at these angles.

Learned this many years ago in Wyoming while shooting across canyons (big washes) at deer and antelope. Forgot the principle one time in Colorado shooting at a downhill bull elk - held just behind the shoulder joint and watched a patch of snow fall off an overhanging fir branch just over it's back. Things like that tend to stay in your memory bank forever!

This is interesting, I never really thought about it, but being here in west texas everything is flat so it doesn't really matter. I'll pay more attention to it when i move to the mountains :D

An easy way to figure out how you have to aim if you are shooting up or down hill is to range to an object that is level with you at that same distance.

If a squirrel is up in a tree and you range to it and it looks to be 30 yards away, look to the base of the tree, range to that and that's the "hold under" distance.

Depending on your angle of approach to the target the hold off might be off a little bit. The reason why this happens, gravity does not react on the bullet to the distance of travel when a bullet is shot on an angle but to the distance of the base leg of the triangle of you to the distance to the target as if it where level to you

The uphill-Downhill phenominon does make a difference. What will make more of a difference is barrel vibration. I assume that you were using a rest. If the barrell or fore end of a contender, (or any gun that does not have a floated barrell), is allowed to touch a solid object when fired, the barrell will recoil away from that object. If the object was a rest that was not very soft, the barrell would recoil upward making the shot hit high.
This can cause dramatic misses.
Sometimes when a rest is not rock hard, but still somewhat firm like a really full sand bag, a gun that is rested closer to the end of the barrell will still jump a little bit causiing a high hit. This may not have anything to do with your observations, but I thought I would mention it.
BRW

I intend to go back and shoot again from the base of the burm and post the results. I guess I didn't realize that such a slight elevation change could have such an effect. I'll check the rest too, as that could be contributing also.

anybody have a spread sheet that calculates holdover in relation to elevation, i did have one made up for archery that would tell me the actual yardage when i was in a treestand and i used a rangefinder to get a distance but i lost it when i had to format my hard drive

anybody have a spread sheet that calculates holdover in relation to elevation, i did have one made up for archery that would tell me the actual yardage when i was in a treestand and i used a rangefinder to get a distance but i lost it when i had to format my hard drive

2 words: BACK UP

everytime I format usually C: (usually at least twice a year)I back everything up onto a separate partition or physical drive. run OS on C and keep files on the other drives, usually don't have to reformat those if the problem is with OS. Sorry back to the question, No I don't have a spreadsheet, sure would like one though for all calibers/bullet weights/powder loads, barrel lengths, etc.etc.etc. :D

Too many factors, BC, angle of elevation or declination, barrel length, drift, velocity

Well let me qualify, there are too many factors to get it dead on...you can get close...but nto dead on...plus you would have to calculate every angle before you went out hunting.

Might work with a bow where you know your angle and weight and "trajectory"...but a little more complex with a gun.

anybody have a spread sheet that calculates holdover in relation to elevation, i did have one made up for archery that would tell me the actual yardage when i was in a treestand and i used a rangefinder to get a distance but i lost it when i had to format my hard drive

i was thinking something more along the lines of a sheet that would correct for rangfinder distances at in a range of elevations eg. if you are 30 feet above your target and your rangefinder tells you its 40 yards to your target. the sheet would correct it to something like (just saying a number) 36 yards.

First of all, HI! New here. I like this forum quite a lot!

BTT, there are "angle corrector devices" for scopes available that show a factor like 0.85 at a given angle with which you multiply the measured range.

I have checked the numbers, it is a simple cosine.

So if you take a pocket calculator to the range, it is fairly easy to calculate the angle if you know the range and heigth offset.
The angle would be

alpha = arcsine (h/d)

h: height
d: line of sight distance to target

If you dont know how to type that in calculators I can post a short instruction too :)

Now you have the angle.
the correction factor for the range is just the numeric value of the cosine, i.e.
c = cosine (alpha)

for 30 degrees either up- or downhill its 0.866, 45° its 0.707, 60° its 0.5 etc.

So lets say you have measured a range of 275 yards to target, and an angle of 25 degrees.
You calculate cosine (25) = 0.906
You mulitply both = 249 yards. so at this angle and range you would not aim with your 275 POA, but with you 250 POA which with heavier slower bullets already is a couple inches difference.

Note that this prediction method only work roughly, since there is an offset between scope LOS and bore LOS, but it should work as a good prediction value.

And as I said previously, some company sells this exact method inside a little device working based on gravity (like those watergauges) for a couple hundred bucks.


Hope that helps a bit,
Regards,
Matt


i was thinking something more along the lines of a sheet that would correct for rangfinder distances at in a range of elevations eg. if you are 30 feet above your target and your rangefinder tells you its 40 yards to your target. the sheet would correct it to something like (just saying a number) 36 yards.

Like I said it would be difficult to come up with a system that does it exactly for all situations. in that a "little" off is a lot off at distance. As well you are measuring the angle of difference and hold over but your are not calculating for the BC nor the effect of gravity. No where in the short form of your calculation do I see the dynamic for trajectory, drift, true optical height, slip, yaw, various effects of overturning..yada yada yada...
Doing sort of isn't really any better than just saying...range to the distance of the target as if it were level to you.

That being said the work we have done on spin detonated rounds has helped us figure some of this out...but the cost for a system that does it truely exact and effective every time ranges in the thousands of dollars.

Considering even the best civilian LRF, can do no better than +/-1 foot...in range and that you seem to be talking about ranges in the hundreds of yards...off a little is still off a bit...

In the end the best way to do this would be to shoot at those angles...at a "middle" distance...and figure out how the gun prints...shooting is improved by shooting...but an interesting metal excercise none the less.

First of all, HI! New here. I like this forum quite a lot!

BTT, there are "angle corrector devices" for scopes available that show a factor like 0.85 at a given angle with which you multiply the measured range.

I have checked the numbers, it is a simple cosine.

So if you take a pocket calculator to the range, it is fairly easy to calculate the angle if you know the range and heigth offset.
The angle would be

alpha = arcsine (h/d)

h: height
d: line of sight distance to target

If you dont know how to type that in calculators I can post a short instruction too :)

Now you have the angle.
the correction factor for the range is just the numeric value of the cosine, i.e.
c = cosine (alpha)

for 30 degrees either up- or downhill its 0.866, 45° its 0.707, 60° its 0.5 etc.

So lets say you have measured a range of 275 yards to target, and an angle of 25 degrees.
You calculate cosine (25) = 0.906
You mulitply both = 249 yards. so at this angle and range you would not aim with your 275 POA, but with you 250 POA which with heavier slower bullets already is a couple inches difference.

Note that this prediction method only work roughly, since there is an offset between scope LOS and bore LOS, but it should work as a good prediction value.

And as I said previously, some company sells this exact method inside a little device working based on gravity (like those watergauges) for a couple hundred bucks.


Hope that helps a bit,
Regards,
Matt

As I said, I just used the basic info, that is, multiply with the factor shown on that device, from this expensive watergauge thingy.

I just ran an online ball comp
http://www.eskimo.com/~jbm/ballistics/calculations.html

Results were quite off.
Baseline:
Stay clear from this watergauge factor device.
It might work for heavy projectiles at short range, where velocity loss is marginal.

Making a table using a ball comp and verify on his own BC and drag function is obviously necessary.

****, cannot remember when I last had such a crappy debut on a forum :D

Regards!

I'm sure that shooting at a target 150 yards away and 23-1/2 feet below you is not going to result in hitting 8-10 inches high. I would check your scope and mounting or the rest you were using might have been to hard.

I'm sure that shooting at a target 150 yards away and 23-1/2 feet below you is not going to result in hitting 8-10 inches high. I would check your scope and mounting or the rest you were using might have been to hard.

A good read on this subject is in the May/June 2004 issue of Pedersen's Hunting, pg. 78, "Uphill, Downhill", by Dick Metcalf; brief, clear, and with only one large diagram. A specific example, is "...standard commercial .30-06 150-grain cartridge fired at a 45-degree angle--not an uncommon shot--from the horizontal (uphill or downhill, doesn't matter). At 300 yards, it will hit about seven inches above where it would hit if fired on level ground." In my view, that's enough to miss the vitals on big game, plus, if the unknowing hunter holds-over, say 3-inches, to compensate for bullet drop, then that's 10-inches high and enough for either a total miss, or cruel wound. In general, because each rifle/cartridge has its one particular trajectory, if you expect long uphill/downhill shots, then fire a few groups at known distances to know exactly how your ammo performs.

Shooting uphill or downhill is a matter of knowing your rifle/load trajectory, and correcting the slope distance to horizontal distance.

The bullet's trajectory is based on the load's velocity and the pull of gravity. Knowing your rifle's trajectory for any given distance cures the first part of the equation, but gravity works perpendicular to the horizontal distance, not the slope distance. If you are aiming at a target uphill or downhill the distance from you to your target in a straight line is the slope distance or the hypotenuese of a right triangle. The horizontal distance is the corrected slope distance to the target where it would be on an level plane with you, or the horizontal base leg of the triangle. The corrected horizontal distance is always going to be shorter than the slope distance. You need to figure out what the horizontal distance is given the slope distance and angle of elevation. After you figure the horizontal distance, it is merely knowing what your rifle's trajectory is at that horizontal distance.

Unless you are shooting at great distances, the angle of elevation won't matter until it exceeds around 15 degrees, or so, depending on the target distance.

I don't think at 150 yards an elevation difference of 20 feet or so would cause your bullet to strike that much higher if holding dead on and scope is zeroed at 100 yards, not at least with something as fast as a .223. I'd check your loads, your scope and mounts, and reconfirm your zero.

A good read on this subject is in the May/June 2004 issue of Pedersen's Hunting, pg. 78, "Uphill, Downhill", by Dick Metcalf; brief, clear, and with only one large diagram. A specific example, is "...standard commercial .30-06 150-grain cartridge fired at a 45-degree angle--not an uncommon shot--from the horizontal (uphill or downhill, doesn't matter). At 300 yards, it will hit about seven inches above where it would hit if fired on level ground." In my view, that's enough to miss the vitals on big game, plus, if the unknowing hunter holds-over, say 3-inches, to compensate for bullet drop, then that's 10-inches high and enough for either a total miss, or cruel wound. In general, because each rifle/cartridge has its one particular trajectory, if you expect long uphill/downhill shots, then fire a few groups at known distances to know exactly how your ammo performs.


Agree whole heartedly with what Mr. Metcalf had to say, but 150 yards is not 300 and a 23 1/2 foot difference in elevation at 150 yards is not much of an angle nowhere close to 45-degrees. I still think his problem has more to do with the scope, the rest, heavier bullets, or hotter loads.

Snuffy, I agree with your comment about 150yds and a 23 1/2 foot difference; something else is the culprit for such short distance and angle. My intent was to put some real data from a reputable source that gave a detailed amount of aiming point change for a common cartridge. Even so, a rifles zero point makes a big difference.

I just had a side-thought that might be off-base, but I'm sure someone will test it. From the Remington website, a .30-06 150 gr. PSP CLU, zeroed at 200 yds. is 8 in. low at 300 yds. For a level or low-angle shot, one would hold-over 8 in. at 300 yds, but if the Pederson's magazine data (7 in. high) is correct, then for a 300 yd. 45 deg. up/down hill shot, one would aim dead-on target because gravity roughly cancels out the drop.

Again the simple answer to this complex question is as follows:

If your target is above or below you...range to something that is EVEN to your height at that same distance. That is the distance that gravity has to effect the bullet.

If you know how much drop you have at given ranges you can plan accordingly.

Again the simple answer to this complex question is as follows:

If your target is above or below you...range to something that is EVEN to your height at that same distance. That is the distance that gravity has to effect the bullet.

If you know how much drop you have at given ranges you can plan accordingly.

Not to nit-pick... because this IS a useful rule of thumb for ordinary hunting ranges (and it's certainly been repeated enough in the magazines), but it's more a coincidence that anything else that the rule works.

However, you have to get into some awfully steep angles, or very long ranges, for this to be wrong (and even then, you're still much closer than if you didn't correct at all).

Most likely, out beyond say 300 yards, especially in the mountains, wind will almost certainly get you before the errors in this rule of thumb will.

The bullets always strike higher on the target when aiming at uphill or downhill shots. You have to practice at varying distances and varying degrees of loft or depression to know exactly where your particular bullet is going to impact at these angles.

Learned this many years ago in Wyoming while shooting across canyons (big washes) at deer and antelope. Forgot the principle one time in Colorado shooting at a downhill bull elk - held just behind the shoulder joint and watched a patch of snow fall off an overhanging fir branch just over it's back. Things like that tend to stay in your memory bank forever!

Kdub......I think it is best for a hunter to learn that principal the hard way! Then one never forgets the next time out on a hunt. I know I sure didn't after missing out on a big whitetail buck, who was standing in a field that was on a 40 degree angle from the creek, going up hill from this hunter and 150 yards away back in the very early 60's. I fired at the buck, who was standing by some brush and a couple of 4 inch diameter trrees. got to see a branch swing down over its back after the bullet cut the limb, late that afternoon on the last day of the hunting season.

I came home and double checked the rifle's zero and it was right on. Some of my friends told me, it was just buck fever. I frowned at that statement. However a man down the road did explain to me, what had happened on my hunt and what to do about it next time out. I took that bit of advice to heart , I made a trip to the lower field and placed some targets up on the hill ridge 150 yards away. Shot those targets and after checking them out, saw where those bullets struck high. I never forgot that bit of valuable information passed on to me.

I'm sure that shooting at a target 150 yards away and 23-1/2 feet below you is not going to result in hitting 8-10 inches high. I would check your scope and mounting or the rest you were using might have been to hard.

Hey Snuffy, How you doing? Yall figured out how to hit that deer standing on the BUTTE yet?

Hey Snuffy, How you doing? Yall figured out how to hit that deer standing on the BUTTE yet?


2Bits, Not doing too bad, how about you. The only way I could hit it would be to get closer.

Thats a very shallow angle. 8/150. Difference from level would be very slight. To the tune of maybe 1/2". I'm with snuffy on this, check everything else.
It is not the result of elevation.

2Bits, Not doing too bad, how about you. The only way I could hit it would be to get closer.

Snuffy I have already had that critter in the freezer many moons ago along with a dozen more over the last 30 years of so.LOL

It looks like that particular post was going no where, other than a half way explanation of formulas and theory's and classroom hocus pocus. I deal with the common FACTS of what it takes to hit the animal quickly (A hunter ain't got all friggin day to make the shot) and it sure isn't co-signs, formulas and theory's, or any other signs get my drift.

If the animal is at a high or low angle, hunter aims low! Now that is passed the 150 yard marker. However at longer distances you best guess again, cause that won't work passed that 400 yard range. Not with a 300 win mag zeroed at 300 yards dead on target. I believe in keeping things real simple like, nothing fancy or setting up a sexton to check the stars or giving a NASA engineer a call on my cell phone, in the middle of the morning.LOL.

Snuffy, I betch if I asked on this forum how long in seconds it took my 300 mag 165 grain bullet going 3200fps, to reach it's target at 400 yards, I will certainly get the correct answer faster than you can say Jack Robinson! I would bet my Old Truck on that fact.LOL.

http://home.sprynet.com/~frfrog/miscellb.htm#angle

Maybe this will shed some light to it.

[edit]
I just ran JBM ballistics online again.
http://www.eskimo.com/~jbm/ballistics/calculations.html

It IS the cosine of the range. I checked my Mildot-Master too, same.

So of you shoot downhill 45 degrees, cosine is 0.707.
Multiply with LOS range. Adjust to calculated range. Hit.

Dont know why I had a mistake in the numbers previously.
It works, try it.

[EDIT]
Man now I get angry :D
MILDOT MASTER has it wrong.
It is the Cosine, but the cosine of the impact point, not the range.

Now again, and this time I double checked:

if you have a ballistic table for impact points of your gun for various ranges.
Determine the impact point for your given range. multiply the impact point with the cosine of the angle. Hold to this aiming point.

Example:
Superelevation for 100m zeroed 308 is roughly 12" at 300m (just a number).
If you determine range to be 300, 30 degrees downhill, cos is 0.866. multiply 12" with 0.866 = 10.3", thats your aiming point. This works same for downhill and uphill.

cos for various angles:
10° - 0.98
20° - 0.94
30° - 0.87
40° - 0.77
50° - 0.64
60° - 0.5
70° - 0.34
80° - 0.17

I know this i an old thread, but I saw this in the brownells catalog last night and I had to post a link
http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=19637

http://home.sprynet.com/~frfrog/miscellb.htm#angle

Maybe this will shed some light to it.

[edit]
I just ran JBM ballistics online again.
http://www.eskimo.com/~jbm/ballistics/calculations.html

It IS the cosine of the range. I checked my Mildot-Master too, same.

So of you shoot downhill 45 degrees, cosine is 0.707.
Multiply with LOS range. Adjust to calculated range. Hit.

Dont know why I had a mistake in the numbers previously.
It works, try it.

[EDIT]
Man now I get angry :D
MILDOT MASTER has it wrong.
It is the Cosine, but the cosine of the impact point, not the range.

Now again, and this time I double checked:

if you have a ballistic table for impact points of your gun for various ranges.
Determine the impact point for your given range. multiply the impact point with the cosine of the angle. Hold to this aiming point.

Example:
Superelevation for 100m zeroed 308 is roughly 12" at 300m (just a number).
If you determine range to be 300, 30 degrees downhill, cos is 0.866. multiply 12" with 0.866 = 10.3", thats your aiming point. This works same for downhill and uphill.

cos for various angles:
10° - 0.98
20° - 0.94
30° - 0.87
40° - 0.77
50° - 0.64
60° - 0.5
70° - 0.34
80° - 0.17
You sir are exackly correct It is the cosine of the angle and aim accordinly your example of a 212 yard hold on a target ranged at 300yards and 45 degrees above or below is spot on

From the perameters you have specified, the results go against all trajectory laws.

If you are shooting from an 25 foot rise in elevation out to 150 yards, the angle of depression is equal to about 3.2 degrees.

As the bullet exits the barrel it rises in an upward arc, let's say if you zero your gun at 150 yards, at 100 yards the bullet will be +.6 inches high and at 200 yards it will be about -2.0 inches low.

Barrel vibration will cause erratic behavior, only if you were shooting rapid fire, overheating of the barrel will cause this type of problem also.

A loose scope or rings, oil in the barrel or not following through with your shot, moving the gun ever so slightly to see were the bullet is going to hit will create this effect.

Wind will play a role in bullet placement but I doubt to the variables you have mentioned.

I personally shoot from high elevations of over 80 feet and out to over 200 yards and have never experienced such results as you. If anthing the bullet will hit short.

Clean your gun, inspect for loose mounts, rings or scope, resight your gun at 100 yard zero and try again.

Make sure your bases are not put on in reverse, I've seen this happen and you'll never get the gun to shoot worth a dime.

Good Luck

Like Lion said there isn't that much drop for a 30-06 over a 300 yard range at a 45 degree angle. I think you got some other factors working here. 20 or 30 feet higher at 150 yards is not going to make a difference in where the gun hits.
Your gonna need to check your zero on a flat place to be sure, but I think your gonna find that something is off in the scope or mounts. check all the screws for tightness. Every once in a while a scope goes bad too.

Good luck in finding your problem, let us know what happens.

Pretty sure after time at the range that it's the scope. I need to upgrade for any reliability I'm finding. Next the ground was hard, so I'm pretty sure the bipod was throwing things off, and there was an intermittent breeze, so together there are a lot of variables.

One thing is sure, when I'm scoping my trophy elk, deer or caribou for a shot, I'll be laying the rifle on a soft pack... not taking any chances there!!!
(note much heavier calibre in above situations!)

Oh dear, time to remember my trig and my vector math from physics.

25 feet high at 150 yards (450 feet) is about a 5.5% ratio, or a little over a 3 degree angle. At that angle, bullet drop (from the bore axis, not the sight axis) due to gravity will be about 5.5% less than it normally would be at that range. Additionally, an acceleration of 5.5% g (1.78 feet per second per second) will be subtracted from the normal loss of velocity, which will reduce the time in flight and therefore further reduce bullet drop very slightly.

With .223 ballistics at that range, I can't see an angle like that making more difference than about a quarter of an inch. I think you need to look for a different cause.

That's cool! Way back in 8/24/04 I predicted 1/2" low by doing the math in my head.