Angle Compensation

[Little Tunny]

For someone who uses a ballistics app and dope cards, and only has a basic rangefinder, how do you deal with angle compensation at longer ranges? I use Shooter and have a couple of cards for varying density altitudes I'm likely to see on a particular hunt. With a mil/mil scope and familiarity with the range of adjustments for varying DAs, it's all fairly easy for me to keep straight in my head (this forum is responsible for converting me to mil/mil, btw, which has been a game changer).

But I guess my fundamental question is: at what range does the angle adjusted range from a relatively cheap rangefinder, like my Sig Kilo 2200, start to screw up the Shooter App solution enough to worry about? I think the Sig manual says something about how it's good to around 400yds, but not sure why or what they are referring to. I understand time of flight starts to become a factor, which would change the wind calls. But for a guy that's trying to hit a deer-sized target at 6-700yds max, does the angle compensated range get me close enough for dialing a correct elevation at those distances?

Unfortunately, I live in the flatlands so can't easily true up steep-angled shots with my particular rangefinder, which would quickly answer my question. Or maybe the answer is, you need to spend $1,200 on a Revic, or use LOS with angle and deal with a more cluttered dope card (e.g., 700yds: -.3@20degrees; -.7@30degrees, etc.). If the angle adjusted range from my rangefinder is garbage, is there a simple, easy to remember analog shortcut similar to wind brackets that will get me in the vitals at 6-700yds? What did folks do 20 years ago?

 

[Ram94]

Is there a reason you aren’t trusting the angle compensated range from your rangefinder?

 

[Little Tunny]

The SIG manual says "AMR is very accurate for shorter distances (i.e.,400yds) and archery," without any further explanation. And again, I haven't actually trued it for anything beyond a few degrees of angle. It's also posed as a sort of academic question to better understand angle compensation at longer ranges.

 

[Ram94]

Interesting.

The way range finders are able to spit out an angle compensated range, which is essentially the horizontal distance to target, and is the span at which gravity is pulling perpendicular to the bullet…is they measure the angle of the rangefinder, cosine that angle and multiply the result by the line of sight distance. For example, if your line of sight distance is 500 yards, and the shot is 30 degrees, you would multiply 500 x 0.87 to get a horizontal distance of 435 yards. I don’t see why that wouldn’t hold true at extended ranges also, but maybe someone else can chime in.

 

[hereinaz]

Don’t use range compensated angles in ballistic solvers. Use the actual range and the look angle.

Here is a thread that might answer your question.

Post in thread 'Help Understanding Energy, Distance, and Angled Shots'
https://rokslide.com/forums/threads...distance-and-angled-shots.331526/post-3314731

 

[khuber84]

Don’t use range compensated angles in ballistic solvers. Use the actual range and the look angle.

Here is a thread that might answer your question.

Post in thread 'Help Understanding Energy, Distance, and Angled Shots'
https://rokslide.com/forums/threads...distance-and-angled-shots.331526/post-3314731

This! My lrf binos with dope will not even give a solution if you're using angle compensated range, only line of site.

 

[Little Tunny]

Thanks hereinaz, I missed that thread somehow! Reading this is a big lightbulb moment for me: "The difference between dope in the 580 45 degree and 410 0 degree happens because gravity also acts over time. The bullet traveling 580 yards spends more time in the air so gravity has longer to act than it does on a bullet traveling 410 yards."

So for my setup, I guess I should probably always set my rangefinder to LOS and become more familiar with the angle adjustments by playing with look angle in Shooter. Hopefully I can create a few simple notes to add to my cards that have nice round numbers. I like having a good base of understanding, but a $1,200 Revic sure does make life easier, doesn't it...

 

[ID_Matt]

Sig 5K is on sale now and will do most of what you want if you aren't wanting to shell out the $1,200 on a revic.

 

[hereinaz]

Thanks hereinaz, I missed that thread somehow! Reading this is a big lightbulb moment for me: "The difference between dope in the 580 45 degree and 410 0 degree happens because gravity also acts over time. The bullet traveling 580 yards spends more time in the air so gravity has longer to act than it does on a bullet traveling 410 yards."

So for my setup, I guess I should probably always set my rangefinder to LOS and become more familiar with the angle adjustments by playing with look angle in Shooter. Hopefully I can create a few simple notes to add to my cards that have nice round numbers. I like having a good base of understanding, but a $1,200 Revic sure does make life easier, doesn't it...

Glad it helps. I use a RF that has the angle sensor and ballistics so I don’t have to think about it.

My set up is Fury with AB that sends environmental including angle to my Garmin watch with AB.

 

[khuber84]

Glad it helps. I use a RF that has the angle sensor and ballistics so I don’t have to think about it.

My set up is Fury with AB that sends environmental including angle to my Garmin watch with AB.

How is the AB garmin watch? I've contemplated trying one out.

 

[hereinaz]

How is the AB garmin watch? I've contemplated trying one out.

It’s awesome. I ran the Garmin 701 for a couple years or more, so knew I wanted a solution on my wrist.

If you don’t have the money for the watch and won’t use it as a watch, try the 701, much cheaper.

 

[Little Tunny]

Attached is a down and dirty chart I put together trying to get a better sense of the corrections I'm dealing with. I'm also trying to find some patterns or rules of thumb I can use in a rush. Still thinking about it all, but one "break over" point seems to be either inside 500yds or inside 15 degrees of angle (maybe a click low will get it done). If either one of those numbers is larger, I probably need to glance at my card (which is when the animal will disappear, and I will be cussing myself for not spending money on a good range finding robot).

I realize I'm reinventing the wheel here, but I just want to fully understand the fundamentals.

 

[hereinaz]

Attached is a down and dirty chart I put together trying to get a better sense of the corrections I'm dealing with. I'm also trying to find some patterns or rules of thumb I can use in a rush. Still thinking about it all, but one "break over" point seems to be either inside 500yds or inside 15 degrees of angle (maybe a click low will get it done). If either one of those numbers is larger, I probably need to glance at my card (which is when the animal will disappear, and I will be cussing myself for not spending money on a good range finding robot).

I realize I'm reinventing the wheel here, but I just want to fully understand the fundamentals.

Man, that is awesome cause it is the way to learn the stuff. It’s like doing the word problems in math.

Yes, inside 500 and less than 15 degrees it doesn’t matter much. Wind errors cause the misses. If the shooter didn’t screw up the shot process first.

The shortcut is learning the trig sine/cosine crap and doing math off the top of your head. All you have to do is blah, blah, blah, math nerd stuff. I have to look it up to explain it…

That ^^^ is why I rely on robots, Hahahha.

 

[ericacymcdonald]

soh-cah-toa

 

[Little Tunny]

Oh yeah, I vaguely remember soh-cah-toa from way back when. Let me know if I'm summarizing this correctly. The trig to calculate side/angle relationships of right triangles gives you the ability to solve for a missing LOS, horizontal distance, or angle only. But once you have those 3 numbers, my understanding is there's an additional ballistics formula/solution factoring in time of flight. Similar to the example in the other thread, I used my numbers plugged into Shooter choosing some real-world scenarios:

700yds @ 30 degrees: 3.6mils (606yd equivalent horizontal distance, if I did my trig correctly)
606yds @ 0 degrees: 3.4 mils

I can only assume the ballistic app is somehow factoring in time of flight (i.e., the time gravity acts on the bullet) to solve for elevation adjustment. That's definitely something I'm letting Shooter figure out for me, and fortunately I think even the most basic rangefinder will give LOS and an angle.

I think I'll probably make a stand-alone angle compensation card, since the ratios don't really change with DA. Then if it's more than 15 degrees or farther than 500yds I can check myself. I also fully recognize these are issues on the fringe of stuff that causes whiffs. I just wanted to run this thought into the ground. Thanks for the input.

 

[hereinaz]

Oh yeah, I vaguely remember soh-cah-toa from way back when. Let me know if I'm summarizing this correctly. The trig to calculate side/angle relationships of right triangles gives you the ability to solve for a missing LOS, horizontal distance, or angle only. But once you have those 3 numbers, my understanding is there's an additional ballistics formula/solution factoring in time of flight. Similar to the example in the other thread, I used my numbers plugged into Shooter choosing some real-world scenarios:

700yds @ 30 degrees: 3.6mils (606yd equivalent horizontal distance, if I did my trig correctly)
606yds @ 0 degrees: 3.4 mils

I can only assume the ballistic app is somehow factoring in time of flight (i.e., the time gravity acts on the bullet) to solve for elevation adjustment. That's definitely something I'm letting Shooter figure out for me, and fortunately I think even the most basic rangefinder will give LOS and an angle.

I think I'll probably make a stand-alone angle compensation card, since the ratios don't really change with DA. Then if it's more than 15 degrees or farther than 500yds I can check myself. I also fully recognize these are issues on the fringe of stuff that causes whiffs. I just wanted to run this thought into the ground. Thanks for the input.

Yeah, the “angle compensated” range from a rangefinder does the trig, on the “shoot to” that is why you need the extra ballistic calculation.

If you do a chart, do it with a ballistic app.

Basically, I have submitted to the robot overlords, lol.

 

[tak]

Oh yeah, I vaguely remember soh-cah-toa from way back when. Let me know if I'm summarizing this correctly. The trig to calculate side/angle relationships of right triangles gives you the ability to solve for a missing LOS, horizontal distance, or angle only. But once you have those 3 numbers, my understanding is there's an additional ballistics formula/solution factoring in time of flight. Similar to the example in the other thread, I used my numbers plugged into Shooter choosing some real-world scenarios:

700yds @ 30 degrees: 3.6mils (606yd equivalent horizontal distance, if I did my trig correctly)
606yds @ 0 degrees: 3.4 mils

I can only assume the ballistic app is somehow factoring in time of flight (i.e., the time gravity acts on the bullet) to solve for elevation adjustment. That's definitely something I'm letting Shooter figure out for me, and fortunately I think even the most basic rangefinder will give LOS and an angle.

I think I'll probably make a stand-alone angle compensation card, since the ratios don't really change with DA. Then if it's more than 15 degrees or farther than 500yds I can check myself. I also fully recognize these are issues on the fringe of stuff that causes whiffs. I just wanted to run this thought into the ground. Thanks for the input.

Here's how I think of it which may or may not help you; seems that we think about the numbers and foundation behind it similarly.

Cosine of the the angle gives you the percentage of the LOS which results in your shoot-to distance.

In your example, Cos 30 = 0.866
So 86.6% of 700 is 606

Your elevation is based off of 606 yards, your windage is based off of 700 yards. That's basically what you need to know. Don't worry about time of flight. My older EL Ranges will give both yardages, so I don't worry about the angle number itself or doing any math in the field.

Now 30 degrees and 700 yards is an extreme example. You pretty much have to to be shooting off a cliff. 20 degrees feels incredibly steep. Anything above 10 degrees hasn't been too common for me. At 10 degrees your shoot-to would be 689 yards and 676 yards for 15 degrees.

5 degrees is 99.6%
10 degrees is 98.5%
15 degrees is 96.6%
20 degrees is 94%
25 degrees is 90.6%
30 degrees is 86.6%

I don't memorize those numbers, but I do reference them when thinking about this topic. And you can use that to figure out what angle and distance may be significant enough to worry about for your type of hunting. As you stated earlier, anything under 15 degrees and 500 yards isn't a huge difference, so that's probably a good rule of thumb. At 15 degrees and 500 yards it's only 0.1mil for me. 15 degrees feels pretty darn steep and 500 yards isn't exactly a chip shot, so most of us should be well practiced and taking a well calculated shot at that point and beyond anyway.

 

[hereinaz]

, so most of us should be well practiced and taking a well calculated shot at that point and beyond anyway.

YES! we’ll practiced. Anything past 400 yards should be giving enough time to range and let your appropriate gadgets do their work. If not, then you won’t be taking that shot.

Practice with them, that’s the problem I see most. They get even less attention than shooting among guys I hunt with. Frustrates me, lol.

I can range and have my dope in seconds. I want to spend time setting up and getting a wind calls.

 

[tak]

YES! we’ll practiced. Anything past 400 yards should be giving enough time to range and let your appropriate gadgets do their work. If not, then you won’t be taking that shot.

Practice with them, that’s the problem I see most. They get even less attention than shooting among guys I hunt with. Frustrates me, lol.

I can range and have my dope in seconds. I want to spend time setting up and getting a wind calls.

for sure, practicing ranging, doping/dialing, and THEN shooting is huge.
NRL Hunter is great for this as well

even ranging, dialing, building a position and dry firing can pay huge dividends

 

[Little Tunny]

Thanks tak, that's a very helpful and practical way of thinking about it all.