Angle offset for Milling

[PBWalsh]

Hello,

So I’m dry firing and while doing so, trying to work on my range estimation with my mil-reticle (I know, just get an LRF, but no money right now for that). Just about every morning, I mil a car tag (12”x6”) and a Chevy symbol (2-7/8”x7”). Every morning I read the 12” wide tag to be approximately .9 mils.

So 12 * 27.778 / .9 = 370 yards.

According to Ballistic Arc, my range should be about 305, so I’d still would get a hit on target, but near the edge to a miss.

I’m ranging off a DIY hog type saddle and cheap tripod, so I’m not getting a super steady image, but I am consistently reading .9 - .95 mils in my SS 5-20 mil-quad at 20x.

I noticed today and yesterday, the vehicle is parked as to where the tag is not a perfect 90* angle to me, but rather offset roughly 15* - 20* away from me (right edge of plate farther than the left edge).

For you math wizards or those that have done this for a while, is there a formula that I can use that can incorporate and angled target. I thought about a SIN COH TAN idea, but dismissed it due to the target (or point of the right angle hypotenuse) being angled and not the linear distance itself.

Any ideas?


Thank you,
- PBWalsh

 

[diverdon]

The thing that will not be effected by the angle the car is parked is the height, unless it is also parked on a slope. Make life easy and mil the height.

 

[Olen_4504]

what he said ^ measure the height, not the width. problem solved.

 

[PBWalsh]

Ok, did that using the center of the reticle (outside of the reticle on 20x gets a tad blurry to my eyes) and got a .51 value (just a hair over .5) and that results to 326 yards, definitely increases my probability of a hit. However, at greater distances, I’d guess the disparity between ranged distance and actual distance would increase.

My other option was to get both the vertical and horizontal results and average the two.

If however, there is an angle, either vertically or horizontally, how can one compute that?

 

[_Windrider_]

Ok, did that using the center of the reticle (outside of the reticle on 20x gets a tad blurry to my eyes) and got a .51 value (just a hair over .5) and that results to 326 yards, definitely increases my probability of a hit. However, at greater distances, I’d guess the disparity between ranged distance and actual distance would increase.

My other option was to get both the vertical and horizontal results and average the two.

If however, there is an angle, either vertically or horizontally, how can one compute that?

IF, and it’s a big IF, you knew the exact angle of displacement from you to the object and IF you knew the exact measurement of at least 1 dimension, you could use trig and good ol pythagoris to figure it out. But that’s a lot of work and it’s still a SWAG at best. If I were presented with this problem, I’d mil something else if I couldn’t just get the vertical dimension as suggested above. You only need 1 dimension to use the formula.

 

[Deleted member 113831]

Ok, did that using the center of the reticle (outside of the reticle on 20x gets a tad blurry to my eyes) and got a .51 value (just a hair over .5) and that results to 326 yards, definitely increases my probability of a hit. However, at greater distances, I’d guess the disparity between ranged distance and actual distance would increase.

My other option was to get both the vertical and horizontal results and average the two.

If however, there is an angle, either vertically or horizontally, how can one compute that?

You use the cosign of the apparent angle to adjust the observed length.

12 x cos of 15* (.965)= 11.58
11.58 x 27.778 = 321.66 / .9 = 357 yards

 

[PBWalsh]

@Skookum Hmm, looks like the angle is 35* according to that formula. My guess of 15* would have been more accurate (than my 90* measurement) though from what you have shown.

12 x cos of 35* (.819) = 9.82
9.82 x 27.778 = 273.05
273.05 / .9 = 303.39

Looks like I have a long way to go in my observation process and angular/linear SWAG measurements.

I definitely appreciate the help!

 

[Deleted member 113831]

@Skookum Hmm, looks like the angle is 35* according to that formula. My guess of 15* would have been more accurate (than my 90* measurement) though from what you have shown.

12 x cos of 35* (.819) = 9.82
9.82 x 27.778 = 273.05
273.05 / .9 = 303.39

Looks like I have a long way to go in my observation process and angular/linear SWAG measurements.

I definitely appreciate the help!

That is why it is better to MIL big stuff rather than small stuff. There is a limit to scope resolution, it isn't necessarily all your fault.

 

[PBWalsh]

Very true, I’d love to see how the same target resolves through a Tangent Theta for comparison.

The tag was a standardized size for measurement.

Plus I’m basically flash milling as my position is shootable, but not steady enough (such as prone) for milling.

 

[Deleted member 113831]

Very true, I’d love to see how the same target resolves through a Tangent Theta for comparison.

The tag was a standardized size for measurement.

Plus I’m basically flash milling as my position is shootable, but not steady enough (such as prone) for milling.

Atmospheric conditions will often limit resolution regardless of scope quality.

 

[PBWalsh]

Oh without a doubt it will. I’m usually doing this exercise at 0630 with the sun coming from the left of the target. Target is in a partially shaded area. Between me and the target are vehicles and white exterior apartment walls that definitely have a glare and flares into the scope image, especially around 0715 as the sun angles higher in the sky.

I understand I’m kinda pushing it as far as conditions go. Would still like to see how a TT controls the flares I described above.

Its a fun exercise that helps both my trigger control, position building, and range estimation.

 

[Deleted member 113831]

Oh without a doubt it will. I’m usually doing this exercise at 0630 with the sun coming from the left of the target. Target is in a partially shaded area. Between me and the target are vehicles and white exterior apartment walls that definitely have a glare and flares into the scope image, especially around 0715 as the sun angles higher in the sky.

I understand I’m kinda pushing it as far as conditions go. Would still like to see how a TT controls the flares I described above.

Its a fun exercise that helps both my trigger control, position building, and range estimation.

I meant to say this the other day, but I applaud your effort to be competent in this. Nobody wants to MIL stuff anymore, and no one talks about it. The method has serious limitations, but you only get to know what those are after you have become proficient at it. When devices fail (and they absolutely will), the man who can revert to alternate methods will overcome and adapt.

You have inspired me to brush up on this skill, as well as a couple of other alternate methods. Thanks.