Range finder in yards an a MRAD SCOPE.

[BigD69]

Hello guys could someone help me out with a question. If you use a rangefinder in yards and have a MRAD SCOPE do you have to convert the math? Thanks

 

[Krieg Hetzen]

Usually you do. However most rangefinders can range in meters and yards. 300 meters is 328 yards which with a .300WM running 180gr Barnes VOR-TX is a 3in difference in impact (if you assume 300 meters=yards). Mainly will depend on target size and distances involved. 3in low on a moose is a whole different ball game than 3in low on a blacktail deer. If you don’t have the capability to range in meters then multiply by 1.094 for approximate or if you’re a stickler then 1.09361. Here’s this for reference:

 

[BigD69]

THANK YOU MAN! I appreciate the answer. So if you measure in meter with the range finder you click aim an shot?

 

[Formidilosus]

I have no idea what is written above.... by no, there is no math involved. A mil is a mil.

 

[Touchdown88]

Nope. Just hit the target with a rangefinder and dial to distance. If you are using the reticle to measure distance, that's an entirely different ballgame.

You can get get milliradian calculator apps that will calculate the distance for you but there are a lot variables that go into using the reticle for precise range estimation.

 

[Low_Sky]

If your range finder is giving you yards, and your drop chart is in yards, there’s no math to do. Just dial for the range according to the chart. Same for meters/meters.

I think you’re getting confused by thinking about using the reticle for range estimation, in which case there is some math involved. Since you’re using a rangefinder, this stuff is irrelevant.


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[DJL2]

The units used for the radius/distance dictate the value of the arc subtended by a Radian/milliRadian. Thus, MRAD are not specific to English or Metric units - a point of confusion for a lot of people.

However, if you want math...light math follows.

A circle is 2*Pi Radian of angle (aka: 360 degrees). If we use 3.1415 as our value for Pi, that's roughly 6.283 Radian. A milliRadian is 1/1000th of a Radian. If there are 6.283 Radian in a circle, there are 6283 milliRadian. That's not to be confused with the military's artillery "mil" scale which is based on 6400 for ease of use. Just some background/trivia.

What's that mean? The circumference of a circle is it's diameter (D) * Pi, or 2* radius (r) *Pi. When we range to a target, we range the radius in this context. You can see from this relationship that the radius (our distance to target) * angle subtended in radians = arc length (or the entire circumference in the case of 2*Pi radians). For example, if our range to target is 1000 yards and our target subtends exactly 1 MRAD, you get 1000 * .001 = 1 yd (1000 yds * 1/1000 Radian). 100 yards, 1 MRAD --> .1 yd. Easy, right? I suppose you could point out we're conflating the arc and the chord...however, the angle is so incredibly small (relatively speaking) that the error introduced is minimal (e.g. 1 MRAD subtends a 1 m arc @ 1000 m with a chord length of .999999958333334 m).

More trivia. Folks like the late Louis Awerbuck have advocated using 18 inches for the height of a human torso when estimating range. You can see an example of that here: Link. You'll note that is 1/2 yd and lends itself pretty well to some fairly clean math, if you go that route.

 

[thinhorn_AK]

If your range finder is giving you yards, and your drop chart is in yards, there’s no math to do. Just dial for the range according to the chart. Same for meters/meters.

I think you’re getting confused by thinking about using the reticle for range estimation, in which case there is some math involved. Since you’re using a rangefinder, this stuff is irrelevant.


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That’s what I do.