View Full Version : effect of up hill angle on zeroing?
been doing alot of shooting at a buddy house who has his own personal range set up in back yard...... pretty sweet. if you have ever seen a hickok45 video on youtube........ its pretty much like his range. only problem is the range is on a hill. we are at the bottom, the further you shoot the further up the hill the targets are.
i just wanted to know what kind off effect does angel or grade have on my zero? if i am zeroed at 50, or 100 yards up on the hill..... am i completely FUBAR at 50, or 100 yards on A FLAT range?
if you dont know what i am talking about here is a fun little 92sf vs p226 where he is using the range almost identical to my buddy's. check it out.
http://www.youtube.com/watch?v=Ph9k3V1mQFc&feature=relmfu
thanks for your input guys.
Doc. Holiday
11-16-12, 10:27
Great question. I've had the same question for both down hill and up hill shooting. I know that it is effected at some point, but I would like to know if there is a "data table" available or an equation that you would just plug in to get your desired results.
If you are zeroed at 100 and shoot uphill at 100, you will hit high.
Shooting Up or Down reduces the bullet drop. A slope doper is used for precision shooting to address this.
Example:
If you have a target at 100 yards and it's a 45 degree up or down angle... the effective range is just over 70 yards.
Using the pathagorean theorem you can calculate the actual flat ground distance to the target and thus the distance that gravity will have an effect on your bullet.
Now within a short range like 100 yards this may be negligible. But if you get out far where the bullet is dropping at a faster rate.... using actual distance with not dope sloping can make you miss the target big time.
kind of hard to believe but trajectory is only affected by the physical reduction of distance due to the angle and is not affected by whether going up or down hill.
that said, at ranges inside about 200 yards and any angle less than about 15% should be negligible within the shooter's and gun's spread of precision. after that there are apps on most any smartphone that can figure it out. I don't have any on my iphone but I've been told that bulletcalc will work. good luck...
kind of hard to believe but trajectory is only affected by the physical reduction of distance due to the angle and is not affected by whether going up or down hill.
Yep.. But that makes it easy. I'd get confused if uphill was different than downhill.
thanks guys.
i am going to call it 25-30 degrees up hill. shooting no more than 100 yards.
thanks guys.
i am going to call it 25-30 degrees up hill. shooting no more than 100 yards.
At 27 degrees, your elevation correction would equal 89.1 yards.
To shoot at a distane that would equal 100 yards for your zero, you'd need to push the target back to 112.23 yards.
Dig?
At 27 degrees, your elevation correction would equal 89.1 yards.
To shoot at a distane that would equal 100 yards for your zero, you'd need to push the target back to 112.23 yards.
Dig?
what app or ballistic calculator did you use for that? i want it.
27deg is steep. Intermediate level downhill ski slope kind of steep. 5/12 roof pitch kind of steep. A normal household stair case is right at 32deg... Is that range actually that steep?
This isn't a tactical app. Geometry and Physics transcends all communities... :p
http://www.csgnetwork.com/righttricalc.html
27deg is steep. Intermediate level downhill ski slope kind of steep. 5/12 roof pitch kind of steep. A normal household stair case is right at 32deg... Is that range actually that steep?
you know what......probably not. if a stair case is 32 degrees.
15-20 degrees is sounding more realistic for the hill we are shooting up.
http://www.youtube.com/watch?v=wTSBcNgGMNo
http://www.mildot.com/
http://www.grc.nasa.gov/WWW/K-12/airplane/tablcos.html
http://www.coretacsolutions.com/pdf/ACI.pdf
The big issue comes from true angle estimation. The overwhelming majority of shooters who don't do much angle shooting calculate the actual angle as being far greater than it really is.
Gravity does not care if you are shooting up or down. The effect of gravity is constant. To calculate the distance use these numbers for cosine of angles...
Cos of angle
10* = .98
20* = .94
30* = .87
40* = .77
50* = .64
60* = .50
70* = .34
80* = .17
90* = no effect
Now you take your line of sight distance (LOS) x Cosine = Flat Range to target. The flat range to target is the actual distance that you will use to set your own dope or make your own adjustments. This assumes that you understand your adjustments on your rifle / load out to distance. So if your looking uphill or downhill and your target is say 500 yards away from your true LOS and your angle is 40* you should set your dope as if you were shooting on a flat range at 385 yards.
500yds x .77 = 385 yds. So your setting / hold off will be for a target at 385 yards and not 500 yards.
15* or less and it is almost meaningless for center of mass type of hits out until 300 yds or so.
http://www.youtube.com/watch?v=wTSBcNgGMNo
http://www.mildot.com/
http://www.grc.nasa.gov/WWW/K-12/airplane/tablcos.html
http://www.coretacsolutions.com/pdf/ACI.pdf
awesome video. thank you!
so lets say my hill is a 20 degree hill and i want a 100 yard zero....
so 100y x 0.94 = 94y .... i zero at 94 yards.
lets say i want a 50 yard zero
50y x 0.94 = 47 ...... i zero at 47 yards.
not a terable difference. thats good i was expecting much worse. and also after watching this video and paying attention to what he said about angles in nature......im probably working with 15 degrees. amazing the more i learn about this the less and less extreme of an angle my hill becomes ;)
http://www.youtube.com/watch?v=wTSBcNgGMNo
Guess I was typing when you posted this, but I checked out the video and said "Hey that's Cleck", lol. He is a really nice guy but a real geek when it comes to the techie side of things. That is not a bad thing either. I completed one of my sniper instructor certs at a place where he was an asst. instructor. If you ever run into him, ask him about his man on a bullet shifting gears analogy. We were drinking beers (a lot of them) and I did an impersonation of him using a beer bottle as the bullet. I'll just say that his sense of humor needs some work. :D
Great guy though!
awesome video. thank you!
so lets say my hill is a 20 degree hill and i want a 100 yard zero....
so 100y x 0.94 = 94y .... i zero at 94 yards.
lets say i want a 50 yard zero
50y x 0.94 = 47 ...... i zero at 47 yards.
not a terable difference. thats good i was expecting much worse. and also after watching this video and paying attention to what he said about angles in nature......im probably working with 15 degrees. amazing the more i learn about this the less and less extreme of an angle my hill becomes ;)This is the big problem, being angle estimation. As you figured out, it really is less meaningful until distances start getting much farther out.
Guess I was typing when you posted this, but I checked out the video and said "Hey that's Cleck", lol. He is a really nice guy but a real geek when it comes to the techie side of things. That is not a bad thing either. I completed one of my sniper instructor certs at a place where he was an asst. instructor. If you ever run into him, ask him about his man on a bullet shifting gears analogy. We were drinking beers (a lot of them) and I did an impersonation of him using a beer bottle as the bullet. I'll just say that his sense of humor needs some work. :D
Great guy though!
This is the big problem, being angle estimation. As you figured out, it really is less meaningful until distances start getting much farther out.
i know. i just a "man, i was waaay off" moment there. we only have access to 100 yards or so on this hill. i am just going to use the COS for 15 or 20 degrees and zero riffles at that distance on the hill.......... probably some where around 90 yards. i think for all intensive purposes it should come out to a true 100 yard zero.
awesome video. thank you!
so lets say my hill is a 20 degree hill and i want a 100 yard zero....
so 100y x 0.94 = 94y .... i zero at 94 yards.
lets say i want a 50 yard zero
50y x 0.94 = 47 ...... i zero at 47 yards.
)
I think you may have read that wrong... If you're 100 yards straight line to the target, but it's 20 Degrees up/down, you correct your dope for a 94 yard shot.
If you want a 100 yd zero and you put your target at 94 yards, you're moving the target the wrong way.. you'd need to push it out to about 104 yards.
Using the above 20 degrees in a CORRECT example:
Lets say you have a 1000 yard shot that requires 10 mils of adjustment in your scope when the shot is level.
If your shot is instead 20 degrees up/down hill at 1000 yards, you'd put dope in your scope for 940 yards.
Are we good?
I can't have you telling people that M4C told you to move your target to 94 yards for an uphill 100 yd zero.
They'll think we're idiots.
Are we good?
I can't have you telling people that M4C told you to move your target to 94 yards for an uphill 100 yd zero.
They'll think we're idiots.
Oh I see. I am still very wrong.
I corrected my 1000 yard example... Not necessarily 9.4 mils... rather your mil adjustment for 940 yards.
So isn't there a formula I can use to figure out where to set the targets on the 20 degree hill to get an honest 100 yard zero?? Sorry about the confusion. I thought the formula using the COS was telling me what distance of upward ground to set the targets.
Yes. That link I provided.
Set the parameters so that the bottom, flat side = 100 units, adjust your angle to the desired slope on "A or B", and calculate.
When you set side "b" to 100 you're locking in your gravity for a flat travel of 100 yards. Click "calculate" to get side "c", which is where you need to move your target.
The calculator above Reconciles to SURF's numbers.
See.. set side "c" to 100 units and angle "A or B" to 10 degrees, and you get his 98 factor posted on pg 1. :)
In the latter example... if you set your target at 100 yards up a 10 degree hill, your bullet will hit like it was shooting at a 98 yard target on flat ground.
Yes. That link I provided.
Set the parameters so that the bottom, flat side = 100 units, adjust your angle to the desired slope on "A or B", and calculate.
When you set side "b" to 100 you're locking in your gravity for a flat travel of 100 yards. Click "calculate" to get side "c", which is where you need to move your target.
The calculator above Reconciles to SURF's numbers.
See.. set side "c" to 100 units and angle "A or B" to 10 degrees, and you get his 98 factor posted on pg 1. :)
In the latter example... if you set your target at 100 yards up a 10 degree hill, your bullet will hit like it was shooting at a 98 yard target on flat ground.
wow. it only comes out to 103.53 for a 15 degree slope. and only 51.76 for 50 yards. that seems so minimal. is this sounding right to you?
btw : thank you all for all the help and resources. it is very much appreciated.
Cool. Now go shoot a 1 inch group.:p
This is some really good info, thanks to all that posted links and calculations. Now if only I had somewhere to actually try it out... It's all pretty flat in this part of Florida.
Magic_Salad0892
11-16-12, 14:10
Thanks for the info Mark/Surf. I was actually gonna ask about stuff like this because I wanna start trying it at 4-500m.
Doc. Holiday
11-16-12, 15:12
Thanks for the info guys. Like most, I've been wondering how do shoot at angles. Do you guys know if the range finders that give you an exact angle when you are shooting?
Lieca, Leupold, etc will make them. They will give you the corrected distance for "slant range" Like Surf mentioned, until you start getting the sharper angles AND distance, don't worry to much. What you need to know on top of this is your drop for all ranges you will be shooting in, down to the 25 yard interval if further out. Also, look at the max point blank range to see if it's even an issue with most hunting situations. Exbal I know has this in the program, of course target size comes into play. There's so many things you can do with adjustable optics, you just have to get a good zero at x distance, know come ups/hold over/unders and have at it. You can even dial up to let's say, 300 and know what you have to hold over/under also(which is easy if you already know what they are for each interval. Oh-I wouldn't worry about 6 yards at 100 if hunting If not wanting to zero at odd distances, just zero at let's say 200 and know what the trajectory is at 100 and 300. For instance my 30-06 is zeroed at 200, it's 1.7 inches high at 100 and drops 7.3 at 300(according to the program and my poor skills) So, at 100 I don't worry and if I shot at 300, I would hold over a tad to stay within a standard east coast whitetail kill zone. If I had a scope with dials, I could dial up 2.5 minutes or .7 mils
One read
http://en.wikipedia.org/wiki/Point-blank_range
http://www.jbmballistics.com/ballistics/calculators/help/traj/traj_exp.shtml
Guess I was typing when you posted this, but I checked out the video and said "Hey that's Cleck", lol. He is a really nice guy but a real geek when it comes to the techie side of things. That is not a bad thing either. I completed one of my sniper instructor certs at a place where he was an asst. instructor. If you ever run into him, ask him about his man on a bullet shifting gears analogy. We were drinking beers (a lot of them) and I did an impersonation of him using a beer bottle as the bullet. I'll just say that his sense of humor needs some work. :D
Great guy though!
This is the big problem, being angle estimation. As you figured out, it really is less meaningful until distances start getting much farther out.
He seems to explain things rather well, sounds like a character!
wow. it only comes out to 103.53 for a 15 degree slope. and only 51.76 for 50 yards. that seems so minimal. is this sounding right to you?
yes. and if you'll check a trajectory table for a 100yd zero you'll see the POI should be within the precision factor of all but the most accurate shooter/barrel/ammo combinations.
I never worry about this except to think to myself, "if it's really steep uphill or downhill shot, hold a little low"...
again, thank you every one for all the resources and info. since i started this thread i have been playing with alot of the calculators and learning alot. i am about to do some thing either clever or stupid, i cant decide. while playing with the hornady ballistic calculator trying to find relationships between zeros on an angle and flat range zeroes.......i discovered that if i zero at 60 yards i get a more a generous zero than either 50y or 100y zero with my particular load. it is very comparable to other zero's .....just with alot less hold over/under. basically my POI never really leaves my 2 moa dot more than .5" or so from 50-250 yards. no drastic difference from a 50 or 100 zero.......just a bit more generous. is this retarded? has any one ever used a "custom" zero?
thought about starting a new thread on this but didn't want to clog up the forum with any more retardation than i have to.
again, thank you every one for all the resources and info. since i started this thread i have been playing with alot of the calculators and learning alot. i am about to do some thing either clever or stupid, i cant decide. while playing with the hornady ballistic calculator trying to find relationships between zeros on an angle and flat range zeroes.......i discovered that if i zero at 60 yards i get a more a generous zero than either 50y or 100y zero with my particular load. it is very comparable to other zero's .....just with alot less hold over/under. basically my POI never really leaves my 2 moa dot more than .5" or so from 50-250 yards. no drastic difference from a 50 or 100 zero.......just a bit more generous. is this retarded? has any one ever used a "custom" zero?
thought about starting a new thread on this but didn't want to clog up the forum with any more retardation than i have to.
from what can tell on ballistic calculators......zeroing any where from 50-100 still gives you acceptable results further down range. is there any reason i should not use a 60yard zero if it is giving me optimal results down range with a rds?
Doc. Holiday
11-19-12, 09:09
Lieca, Leupold, etc will make them. They will give you the corrected distance for "slant range" Like Surf mentioned, until you start getting the sharper angles AND distance, don't worry to much. What you need to know on top of this is your drop for all ranges you will be shooting in, down to the 25 yard interval if further out. Also, look at the max point blank range to see if it's even an issue with most hunting situations. Exbal I know has this in the program, of course target size comes into play. There's so many things you can do with adjustable optics, you just have to get a good zero at x distance, know come ups/hold over/unders and have at it. You can even dial up to let's say, 300 and know what you have to hold over/under also(which is easy if you already know what they are for each interval. Oh-I wouldn't worry about 6 yards at 100 if hunting If not wanting to zero at odd distances, just zero at let's say 200 and know what the trajectory is at 100 and 300. For instance my 30-06 is zeroed at 200, it's 1.7 inches high at 100 and drops 7.3 at 300(according to the program and my poor skills) So, at 100 I don't worry and if I shot at 300, I would hold over a tad to stay within a standard east coast whitetail kill zone. If I had a scope with dials, I could dial up 2.5 minutes or .7 mils
One read
http://en.wikipedia.org/wiki/Point-blank_range
http://www.jbmballistics.com/ballistics/calculators/help/traj/traj_exp.shtml
Cool thanks Mark. Good info.
Thanks for the info guys. Like most, I've been wondering how do shoot at angles. Do you guys know if the range finders that give you an exact angle when you are shooting?
The Bushnell ARC series of LRFs will give you the angle-compensated range. They won't tell you the angle, just calculate it. Lase something at 322 yards up a 20 degree incline in ARC mode, it'll show you 302.5 yards.
Also, you can use a scientific calculator to figure out your exact cosine right quick - in degree mode, punch in the angle and his "cos". Bam, there's your correction factor.
Or, if you do a lot of angle-shooting, they make cosine indicators that bolt on to your rifle and actually tell you the angle and cosine for that angle.
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