High angle wind calling - LOS vs "shoot to" range

[Antares]

Fair warning: I'm not feeling real smart today so this might be hard to follow or a dumb questions....or a dumb questions that's hard to follow. Enjoy!

How do you deal with making wind calls on high angle shots when there's a significant difference between the line of sight (LOS) range and the "shoot to" (true ballistic range, horizontal distance, corrected range, etc.) range?

You need to dial elevation based on the corrected range, but you need to hold wind based on the LOS range, right?

Here's an example using big numbers to illustrate my point (I just pulled these out of the Hornady solver, tell me if you see something really off). I'm shooting my 6.5CM (140 ELDM @ 2730). I have a target at 1000 yards (LOS range) and 30 degrees downhill. There's a full value 10 mph crosswind. I range it and get a corrected range of 750 (I'm using a Leupold RX-1600i TBR/w). So I need 19.2 MOA of elevation. Now the wind...at 750 yards I need 4.9 MOA, but that's for the corrected range...I actually need more like 7.1 MOA because the LOS range is 1000 yards, correct?

So what's the solution here?

- Do some range finders display corrected and LOS range at the same time?
- My range finder will show both, but not at the same time and I don't want to be cycling between functions.
- I could use the LOS setting because it displays angle, but then I'd need to put in into a ballistic solver. This is not ideal because I prefer trajectory cards. (I'm guessing this is the answer.)
- You'd have the same problem if you were using a CDS dial. You'd have your corrected range to dial, but you'd still need LOS range for your wind call.

I'm I confused? Making it too complicated? This is all hypothetical, but I'm curious what others have to say. Thanks for reading.

 

[Reburn]

My answer. Hell I dont know. Interested to see the answers.

My short answer. If I could get prone and setup and felt really solid. AND could toggle my rangefinder back to true distance I would let my ballistic app of choice handle that equation and I would guess at a thousand yards I would have plenty of time to do so as the animal should be unaware of me. If it was aware and they were spooky I wouldnt be taking that kinda shot anyways. Then I would just let the calculator do the math. Wind value calls have less to do with true yardage as they do velocity as it relates to distance traveled and time of flight.

 

[willfrye027]

I’m not an expert so take this with a grain of salt… I’d think the LOS (longer) distance would matter because that will reflect the wind pushing your bullet from you to the target. It has to physically travel through the wind that far.

I’m assuming you are thinking hunting situations here. I don’t think this will be a factor even with a steep angle and pretty long shot. If you miss, it will be from misjudging the wind mph or direction, thermals, etc. Plus at that range now you’re thinking about spin drift and other factors. It’s just hard for me to imagine a situation where this would be an issue hunting even at the outer limits of your 6.5cm range.

 

[Flatgo]

First you’ll miss every time on elevation using angle modified range at a 1000 yard and 30 degree angle. You’ll need to run that calculation through a good ballistic calculator using los distance and angle. The calculator will also give you a wind hold based on los distance. Angled shots are very difficult and not all ballistic calculators even make the right correction. As a public service announcement AMR only is valid on shots less than about 500 yards and angles less 20 degrees. After that the approximation starts to become invalid.

 

[ElPollo]

I am no expert or internet sniper, so take this with a grain of salt. I would suggest you are overthinking and getting into analysis paralysis. I don’t use LOS distance at all and never switch my rangefinder to that mode.

In the field when you have conditions where you have multiple wind speeds at different distances, the best you can do is estimate using mirage and average it in your head. You may know it is 7.5 mph where you are sitting, but you are just estimating wind speed where it’s blasting through the middle of the canyon between you and your target based on mirage. You are going to make a series of assumptions and decide on your solution based on them. If it’s a full value wind and the wind is an estimated 15 in the canyon and the target you can slot wind speed in the middle. If you are in a small protected spot, you may disregard the 7.5 measurement all together and use the estimate of 15. If conditions are the same on both sides with 15 in the middle, you estimate on the low side of the average.

Point is that it’s math, but you can make it over complicated without improving your accuracy in the field. IMO it’s better to spend your time practicing reading the wind speeds than figuring out different ways to calculate stuff. But your mileage may vary.

 

[JimGa]

TK is correct

 

[Harvey_NW]

Don't forget to throw in twist and which direction crosswind jump is going to affect your elevation..

 

[ElPollo]

I don’t disagree with TK. But I think in field conditions in the mountains, most people’s error rate on wind calls exceeds the difference between wind drift for horizontal and LOS distance. If you are able to make those wind calls with consistency in the mountains, then adding this math to your solution process may be worthwhile. My shooting history in the field has not shown a need for it.

 

[Antares]

Elevation correction based on equivalent horizontal distance.

Windage correction based on line of sight distance.

Yes, thanks for confirming, but that wasn't really the heart of the questions. I was more just laying out some background. The real question is how do you deal with it?

The example I laid out is extreme and in that scenario it would be best to use a solver. But what about in the 600 yards range? What would you do if you didn't have a solver? Toggle between corrected and LOS range in your range finder and then reference your trajectory card (taking elevation from the corrected range and windage from LOS range)? Just forget about it and say the difference is less significant than your wind call error?

Just curious because I was watching a Thomas Haugland video and he was making a high angle, 880 m shot and it looked like he was doing it off trajectory cards (not a solver).

 

[AZ_Hunter_2000]

According to "shooterscalculator.com" and using 143 gr ELD-X in my 6.5 CM (2726 fps), 200 yard zero (hits 1800 fps about 750 yards), a 10 MPH crosswind at 90*, and incremental shooting angles:



There is not that much of a difference going from a 0* to an 89* shooting angle when it comes to wind drift (inches).

What am I doing wrong?

 

[Harvey_NW]

What am I doing wrong?

Not accounting for the difference between angle compensated distance and LOS for the shot.

If you range a rock at 1,000 but it's at a 30* angle and your rangefinder compensates and tells you dial for 900, you still need to use a windage value of 1,000 because that's the LOS distance. So if you used your rangefinder for compensated distance and referenced off the chart, you would be using the wrong windage drift value of 55.07 instead of 70.44.

 

[AZ_Hunter_2000]

Not accounting for the difference between angle compensated distance and LOS for the shot.

If you range a rock at 1,000 but it's at a 30* angle and your rangefinder compensates and tells you dial for 900, you still need to use a windage value of 1,000 because that's the LOS distance. So if you used your rangefinder for compensated distance and referenced off the chart, you would be using the wrong windage drift value of 55.07 instead of 70.44.

Fair enough. Then why do calculators include shooting angle? This is from shooterscalulator but Strelok (for example) has something comparable.

 

[Harvey_NW]

Fair enough. Then why do calculators include shooting angle? This is from shooterscalulator but Strelok (for example) has something comparable.
View attachment 349256

For when you're using LOS distance. You can get a line of site range for a correct wind value, and then input your angle off your cosine gauge into your calculator for your elevation correction.

The only other way I can come up with would be to use the angle compensated distance from the rangefinder, and then do the math backwards on the cosine gauge to get your LOS distance for your windage correction. Either way, some math involved.

I use Strelok and prefer to leave my angle zeroed on my calculator, and input my compensated range from my rangefinder. Then wind holds are just instinctive from practice. The steeper the shot angle, give er a little more. On targets of course, if there's enough wind I need to do long hand math to shoot at an animal, I can probably close some distance.

 

[AZ_Hunter_2000]

For when you're using LOS distance. You can get a line of site range for a correct wind value, and then input your angle off your cosine gauge into your calculator for your elevation correction.

The only other way I can come up with would be to use the angle compensated distance from the rangefinder, and then do the math backwards on the cosine gauge to get your LOS distance for your windage correction. Either way, some math involved.

I use Strelok and prefer to leave my angle zeroed on my calculator, and input my compensated range from my rangefinder. Then wind holds are just instinctive from practice. The steeper the shot angle, give er a little more. On targets of course, if there's enough wind I need to do long hand math to shoot at an animal, I can probably close some distance.

Gracias