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Looking for Answers regarding TMR/mil formula

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 09:40
mac1776 View Drop Down
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Gents,

In the Stan right now, word around is that there is a new method of Range E using the TMR. Essentially you place your TMR "dash" at the base of your target and turn your elevation knob and count the amount of minutes it is raised and then plug it into the formula. Problem is we don't have the formula and would absolutely love to have that for ranging odd objects rather than collecting data on every single possible size dimension that exists here. If anyone can help it would be much obliged. Thanks fellas (and ladies if there is any).

-Mac
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 10:55
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The primary problem I see with that method is you need a way to lock the gun in position where it is absolutely immovable.  Bump the gun during this process and the whole thing fails, and you're some possibly forgotten number of clicks off zero.

Add to that the simple fact that many (MANY!) scope mechanisms, though consistent, are not exactly 1/4MOA clicks.

All in all, it is a very bad way to do what can be done on the reticle - and with more precision.

In theory, it can work, but you need a way to completely immobilize the gun during the process, and you need to verify the scope's precision in click values (and consistency in click values.)


And thank you for your service.

If you do hear how this works (and it works well), please let us know.

Or maybe it's just me.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 12:49
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Gents,

Agreed this is more difficult. However, the purpose of this formula is a way to measure the height of a target without knowing range (then plugging into your mil-relation formula). For instance while in a theoretical hide site, we would use this as a back up to LRF and eye estimation (if all suddenly failed, MURPHY) in order to form our target reference points. This formula was mentioned to us by a former unit member who now works at the US Army Sniper School. It is supposed to be quite helpful in the event we come across an object of unknown size. While I agree that it will take much more time and prove more difficult to master at first I believe in having all the tools in the mental toolbox. Thanks for the response though.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 13:51
mac1776 View Drop Down
Optics GrassHopper
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I am also asking this question on multiple sniper/shooting forums. The feeback I am getting the essentially the same so I am going to break it down to further clarify. So to address your question I will restate mine.

Without knowing the range I would need to use the standard mil-relation formula. We use this (as I am sure you do, but Marines use yards versus meters)

Target size in inches x 25.4 divided by mil reading = distance in meters

So I have two unknowns the target size and the range, but I do have a mil reading.

So this unknown formula would allow me to inversely find out the target size in inches thus allowing me to plug it into my mil-relation formula. This is all assuming I have no LRF my eyes are not getting me a good range, and I have no mil-dot master.

I don't need to do this, this is just me and my teams trying to build the arsenal of knowledge. I tried contacting my buddies at the school house but to no avail. I appreciate you taking the time to respond and work through this with me and my restating of the question was not me "breaking it down barney style" just trying to more accurately explain my question
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 14:04
Graysteel View Drop Down
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I have to agree that it would be nearly impossible to hold the rifle steady enough to accomplish this with any real accuracy. I also think there may be a misunderstanding (perhaps on my part) about how this is supposed to work. If you turn the elevation knob you are making an angular change which will always read 1 for 1 on a reticule. In other words, if you adjust 1 mil up on the dial you will always be one mil up on the reticule regardless of the size of the target. I know of no way in Trigonometry to get both range and size given only one angle.

It is possible to get range to a object of unknown size from two different millings that are taken at two different unknown distances as long as the difference between the distances is known.  Meaning if the distance is X and if you have a milling at X and a milling at X+100 meters you can back into the range.  I think there is some missing information in what you were told.


Edited by Graysteel - July/24/2010 at 14:10
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 15:20
Rancid Coolaid View Drop Down
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Mac,  you want an equation (with 1 "known") for deriving 2 unknowns, each being a function of the other.  I'm a little rusty on my mutliple-variable calculus, but I do not think what you wish to do is doable - in any way that will be effective in a combat environment.

Curious to know what other shooters say.


I have some old cold war-era cards I was issued with the exact dimensions of each Soviet piece of battlefield hardware, those are useful.  We drew everything up in a similar fashion in the old days (laser target designators but pre-range-finder.)  Back then, it was measure everything you could find, log it in your data book, carry on. 

Let me know how this goes.

Or buy a laser rangefinder and keep spare batteries around.

I haven't been at the forefront of combat shooting for awhile, but I am fairly certain what you wish to do is undoable in combat.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 15:43
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Exactly. I also don't see how the math would work for 2 different unknowns in the same equation unless this guy would approximate range with the eye. It's very accurate to rangefind with the turret assuming the gun is steady since u could theoretically divide a .25 MOA, IPHY, whatever the unit into tenths, from the very last click that takes u above the target. This would give a rangefinding accuracy level of ~ .025 MOA, etc.
 
I've worked a lot with the mil-ranging formula. The most important aspect of rangefinding with any reticle is the flexibility of the mil-ranging formula, NOT IT'S APPLICATION TO THE MILLIRADIAN UNIT OF MEASURE! As it turns out it's most basic form defines not only rangefinding with any reticle/turret but also downrange zeroing as well. Here it is copied from another forum--
 
It's all based on the most basic form of the mil-ranging formula, because a bullet drop at any distance is the same sort of dimension as a target size when referenced with an optic (turrets or reticle). Any other formula given will be a simplification or rearrangement of this--

bullet drop (") x range of reticle subtension or turret value measurement (usually 100 yds.) / reticle or turret subtension (") / "mil-reading" or turret clicks (decimal equivalent) = range (yds.)

Looks complicated, super-simple to apply. Hows about 10" low at 400 yds. with 0.25" per hundred yd. turret clicks as OP suggests.

10 x 100 / 0.25 / X = 400

X=10 clicks

Now if u have a turret that's graduated in 1.0 inch per hundred yd. numbers then--

10x100/1.0/X=400

X=2.5 whole # graduations.

Repeating interval reticles (rangefinding reticles mostly) are the same way and ballistic reticles require 1 more calculation to get the dope.

Rangefinding with reticles is the exact same system just replace bullet drop with tgt. size ("). This time range is the unknown once the "mil-reading" (or even turret click) is determined.

Now simplify and/or rearrange as desired.
 
When i use the TMR reticle for rangefinding i use a factor of 138.9, since i'm attempting the highest degree of rangefinding accuracy for every reticle i use. 138.9 comes from 100 yds./0.72" since that's the subtension between each .2 mil. (actually i even go further by subtracting 1 line thickness since interpolating between line stadia will be more accurate this way--just a theory of mine and Darrell Holland's. Certainly easy to prove if i ever get the time). Too many guys use the TMR incorrectly, and they try to use it to interpolate (guessing the mil-reading between stadia points) only to a level of 0.1 mil. Interpolating to a level of .02 mil is WAY more accurate. Suppose there is a 10" target that occupies 3.4, .2 mil TMR units. Then here it is--
 
10 x 100  / .72 / 3.4 = 410 yds.
 
You MUST understand this formula backwards and forwards (i have committed it to memory) and apply it with every multistadia reticle i use for rangefinding from simple plex to mil-dot to Ballistic Plex. It's very easy to calculate tgt. size  from known range and tgt. size "reverse milling". There is 1 additional calculation for rangefinding with a multi-stadia reticle that doesn't repeat it's subtension (ballistic reticles). Here's a link to rangefinding using the mil-ranging formula with any reticle-- www.ottllc.com/specialtypistols/sp20.pdf (Item C-Reticle Rangefinding).
 
Hope this helps some.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 15:59
sscoyote View Drop Down
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To sum up here, the main points are--

 

1) The mil-ranging formula is not specific to the milliradian unit of measure

2) It can be used for rangefinding and downrange zeroing with any reticle OR TURRET click value.

3) Although it's based in trigonometry, the simplification of the formulas require only algebra to apply it.

4) Commit to memory all 5 unknowns of the equation for best results.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 16:19
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To sum up even more, somebody was confused somewhere along the line when they set you on this path.

It cannot be done.  You cannot solve for two unknowns without two equations with different unknowns.  Both of your equations have the same unknowns--target size and distance.

You can estimate target size, if you know the distance.

You can estimate target distance, if you know the size.

If you don't know either, you're stuck.

The only thing the "new" method of measuring (using the elevation turret to get MOA instead of the reticle to get Mils) gets you is MOA instead of Mils.  This may be useful for somebody who doesn't know the mil formula or likes to do the MOA/inches math instead. 

But that's all it gets you.  It won't magically solve an equation with two unknowns.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/24/2010 at 23:43
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Jon--he may be estimating tgt. distance. That would net tgt. size to some degree of accuracy. That's the only solution that i can see.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 02:30
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Correctly, you can have one equation with two unknowns, but there will, except for special conditions, be more than one solution... unacceptable for precision shooting purposes. 
There is nothing magic about the TMR reticle that would allow you to overcome the requirements for "knowns"...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 03:57
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Let me ask a stupid question,if he is guesstamating on distance lets say,then he already has one known fact,all be it a guess?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 05:53
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In the scenario described, either distance or target size can be estimated and the other derived.  However, the "goodness" of the estimated variable value will determine the "goodness" of the solution.  Estimating skills are crucial...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 07:12
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In real life the variables in bullet drop are tempered by the muzzle rise of the M240 Bravo and the proximity of close air support.

Edited by Urimaginaryfrnd - July/25/2010 at 07:14
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 09:20
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Good point...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 11:45
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In the precision fire game, there are no "estimations", else you lose the "precision" in the fire.

Act accordingly.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 12:01
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Cheers
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 12:50
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Which piece of equipment used in precision fire gives "exact" measurements?  LRF?, RADAR?...  when your eye is used to "measure" the angle (MOA or mils) subtended by a target of known size, is that exact or an estimate?  When you "measure" wind, either with a windsock/flag, Kestrel wind meter, or mirage... exact or estimate? 

"... then I will try to make the best estimate that I can..."
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/25/2010 at 20:40
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Exact.

Dammit!


There's one in every crowd.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/26/2010 at 08:12
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Accuracy is in regard to the methods used for the approximation of the measurement. As in trig. is an accurate measurement method.
Precision is how many places to the right of the decimal you want it.


Edited by Dale Clifford - July/26/2010 at 08:18
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/26/2010 at 14:36
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Pontification serves no purpose...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/27/2010 at 01:42
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/27/2010 at 20:30
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Originally posted by Kickboxer Kickboxer wrote:

Pontification serves no purpose...
Sorry about that- you sounded confused in your ramblings.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/28/2010 at 13:43
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My concern is that Mac who is currently trying to apply this theory in an unfriendly environment understands why folks are saying that it cannot be done.

The issue is that in this case you simply do not have enough data to solve the problem. While there are ways to solve for both an unknown distance and an unknown object height, they all require more data. Either you have to have two millings of the object from two different distances and know the delta between the distances or you can triangulate distance if you have a very accurate vector from two points. Both cases require additional information. Triangulation can be useful if you have two different LP/OPs or hides that have communication between them.


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