Is there a formula to use the mil reticle on on a variable power scope other than the power it is set from the factory? What I mean is I just bought a Vortex Viper and the correct mil power is 14x. Is there anyway to find out what the spacing is between the dots at say 6.5x or 20x?
Rifle Scopes Mil-Dot Question
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Re: Mil-Dot Question
Sort of but it takes some work.
https://www.snipercentral.com/forums/viewtopic.php?t=16137
Sort of but it takes some work.
https://www.snipercentral.com/forums/viewtopic.php?t=16137
Re: Mil-Dot Question
The problem with that thread on snipercentral is that much of the math is incorrect.
A problem with attempting to do that is that the power rings are often not precisely calibrated.
Go to this link: Optically Checking Rifle Scopes
Follow the instruction in the section entitled "Using Second Focal-Plane Scopes at Half Power" to first check the power at which your reticle is correct, and then to calibrate a point which is half of that power.
As far as using it at other powers, if you assume that the reticle marking is correct, you can use this formula:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
calibrated reticle power
reticle spacing (mils) = ------------------------
indicated reticle power
</pre></div></div>
So, if you have two reticle marks which are 1 mil apart at the calibrated power of 14, at 20 power those marks are 14/20 mils apart, or 0.7 mils apart.
I suspect that's not a very useful result, but there you go.
The problem with that thread on snipercentral is that much of the math is incorrect.
A problem with attempting to do that is that the power rings are often not precisely calibrated.
Go to this link: Optically Checking Rifle Scopes
Follow the instruction in the section entitled "Using Second Focal-Plane Scopes at Half Power" to first check the power at which your reticle is correct, and then to calibrate a point which is half of that power.
As far as using it at other powers, if you assume that the reticle marking is correct, you can use this formula:
<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
calibrated reticle power
reticle spacing (mils) = ------------------------
indicated reticle power
</pre></div></div>
So, if you have two reticle marks which are 1 mil apart at the calibrated power of 14, at 20 power those marks are 14/20 mils apart, or 0.7 mils apart.
I suspect that's not a very useful result, but there you go.
Re: Mil-Dot Question
When i 1st started to investigate mil-ranging i kept on coming across this formula--
tgt. size (") x 27.78 / mil reading = range (yds.)
I kept wondering where did this 27.78 factor come from? Well it's actually a simplification of this--100/3.6, which is what i now refer to as the "subtension unit". I knew at the time that the mil-dot was 3.6" at 100 yds. So i thought shouldn't it also work for any subtension at any range? Turns out it does and it works perfectly from simple plex to Ballistic Plex to mil-dot. All u have to know is the subtension between any 2 points at any range and that subtension can be substituted into the "mil-ranging" formula SU variable. I use my Nikon Buckmasters 6-18x mil-dot for rangefinding at the optic's highest power (18) where it becomes 2.4 IPHY between dots, so my "SU" is now 100/2.4 = 41.667. The beauty of it all really is that in a 2nd focal plane reticle the dot to dot-to-dot relationship remains the same no matter what power (subtension) you're on. So the .2 "mil" dot will always be .2 of whatever dot to dot subtension you're using---that's a very nice thing!
This concept is way bigger than the mil-dot itself. Because it means that u can now rangefind (and downrange zero, BTW, since the "mil-ranging" formula defines that also) with any reticle at any power--oftentimes more accurate than the mil-dot itself (don't tell any of the guys here that though).
When i 1st started to investigate mil-ranging i kept on coming across this formula--
tgt. size (") x 27.78 / mil reading = range (yds.)
I kept wondering where did this 27.78 factor come from? Well it's actually a simplification of this--100/3.6, which is what i now refer to as the "subtension unit". I knew at the time that the mil-dot was 3.6" at 100 yds. So i thought shouldn't it also work for any subtension at any range? Turns out it does and it works perfectly from simple plex to Ballistic Plex to mil-dot. All u have to know is the subtension between any 2 points at any range and that subtension can be substituted into the "mil-ranging" formula SU variable. I use my Nikon Buckmasters 6-18x mil-dot for rangefinding at the optic's highest power (18) where it becomes 2.4 IPHY between dots, so my "SU" is now 100/2.4 = 41.667. The beauty of it all really is that in a 2nd focal plane reticle the dot to dot-to-dot relationship remains the same no matter what power (subtension) you're on. So the .2 "mil" dot will always be .2 of whatever dot to dot subtension you're using---that's a very nice thing!
This concept is way bigger than the mil-dot itself. Because it means that u can now rangefind (and downrange zero, BTW, since the "mil-ranging" formula defines that also) with any reticle at any power--oftentimes more accurate than the mil-dot itself (don't tell any of the guys here that though).
Re: Mil-Dot Question
So what you are saying is:
subtension unit = range(yds) x mils / tgt size(")
with "su" to be determined for each power by measuring mils at a known range and target size?
Interesting concept.
So what you are saying is:
subtension unit = range(yds) x mils / tgt size(")
with "su" to be determined for each power by measuring mils at a known range and target size?
Interesting concept.
Re: Mil-Dot Question
Thanks for the replies. I will try this when I get my scope mounted. I was not aware of just how fast Liberty Optics Ships orders. My scope was delivered Friday but the rings won't be here till Monday. Waiting is hard.
Thanks for the replies. I will try this when I get my scope mounted. I was not aware of just how fast Liberty Optics Ships orders. My scope was delivered Friday but the rings won't be here till Monday. Waiting is hard.
Re: Mil-Dot Question
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sscoyote</div><div class="ubbcode-body">When i 1st started to investigate mil-ranging i kept on coming across this formula--
tgt. size (") x 27.78 / mil reading = range (yds.)
I kept wondering where did this 27.78 factor come from? Well it's actually a simplification of this--100/3.6, which is what i now refer to as the "subtension unit". I knew at the time that the mil-dot was 3.6" at 100 yds. So i thought shouldn't it also work for any subtension at any range? Turns out it does and it works perfectly from simple plex to Ballistic Plex to mil-dot. All u have to know is the subtension between any 2 points at any range and that subtension can be substituted into the "mil-ranging" formula SU variable. I use my Nikon Buckmasters 6-18x mil-dot for rangefinding at the optic's highest power (18) where it becomes 2.4 IPHY between dots, so my "SU" is now 100/2.4 = 41.667. The beauty of it all really is that in a 2nd focal plane reticle the dot to dot-to-dot relationship remains the same no matter what power (subtension) you're on. So the .2 "mil" dot will always be .2 of whatever dot to dot subtension you're using---that's a very nice thing!
This concept is way bigger than the mil-dot itself. Because it means that u can now rangefind (and downrange zero, BTW, since the "mil-ranging" formula defines that also) with any reticle at any power--oftentimes more accurate than the mil-dot itself (don't tell any of the guys here that though). </div></div>
way to be on top of it.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sscoyote</div><div class="ubbcode-body">When i 1st started to investigate mil-ranging i kept on coming across this formula--
tgt. size (") x 27.78 / mil reading = range (yds.)
I kept wondering where did this 27.78 factor come from? Well it's actually a simplification of this--100/3.6, which is what i now refer to as the "subtension unit". I knew at the time that the mil-dot was 3.6" at 100 yds. So i thought shouldn't it also work for any subtension at any range? Turns out it does and it works perfectly from simple plex to Ballistic Plex to mil-dot. All u have to know is the subtension between any 2 points at any range and that subtension can be substituted into the "mil-ranging" formula SU variable. I use my Nikon Buckmasters 6-18x mil-dot for rangefinding at the optic's highest power (18) where it becomes 2.4 IPHY between dots, so my "SU" is now 100/2.4 = 41.667. The beauty of it all really is that in a 2nd focal plane reticle the dot to dot-to-dot relationship remains the same no matter what power (subtension) you're on. So the .2 "mil" dot will always be .2 of whatever dot to dot subtension you're using---that's a very nice thing!
This concept is way bigger than the mil-dot itself. Because it means that u can now rangefind (and downrange zero, BTW, since the "mil-ranging" formula defines that also) with any reticle at any power--oftentimes more accurate than the mil-dot itself (don't tell any of the guys here that though). </div></div>
way to be on top of it.
Re: Mil-Dot Question
Hi you guys got me thinking about this and I have come up with the below chart, maybe somebody could check my maths please.
However I still think it is easier to use a first focal plane scope and measure target size in Millimetres and range in Metres.
target size(mm)/mil measurement =range in metres
simple!!!!
Magnification Mils when showing one mil in scope yards subtension value distance between dots
6.5 2.154 100 59.83 1.67
7 2.000 100 55.56 1.80
7.5 1.867 100 51.85 1.93
8 1.750 100 48.61 2.06
8.5 1.647 100 45.75 2.19
9 1.556 100 43.21 2.31
9.5 1.474 100 40.94 2.44
10 1.400 100 38.89 2.57
10.5 1.333 100 37.04 2.70
11 1.273 100 35.35 2.83
11.5 1.217 100 33.82 2.96
12 1.167 100 32.41 3.09
12.5 1.120 100 31.11 3.21
13 1.077 100 29.91 3.34
13.5 1.037 100 28.81 3.47
14 1.000 100 27.78 3.60
14.5 0.966 100 26.82 3.73
15 0.933 100 25.93 3.86
15.5 0.903 100 25.09 3.99
16 0.875 100 24.31 4.11
16.5 0.848 100 23.57 4.24
17 0.824 100 22.88 4.37
17.5 0.800 100 22.22 4.50
18 0.778 100 21.60 4.63
18.5 0.757 100 21.02 4.76
19 0.737 100 20.47 4.89
19.5 0.718 100 19.94 5.01
20 0.700 100 19.44 5.14
Hi you guys got me thinking about this and I have come up with the below chart, maybe somebody could check my maths please.
However I still think it is easier to use a first focal plane scope and measure target size in Millimetres and range in Metres.
target size(mm)/mil measurement =range in metres
simple!!!!
Magnification Mils when showing one mil in scope yards subtension value distance between dots
6.5 2.154 100 59.83 1.67
7 2.000 100 55.56 1.80
7.5 1.867 100 51.85 1.93
8 1.750 100 48.61 2.06
8.5 1.647 100 45.75 2.19
9 1.556 100 43.21 2.31
9.5 1.474 100 40.94 2.44
10 1.400 100 38.89 2.57
10.5 1.333 100 37.04 2.70
11 1.273 100 35.35 2.83
11.5 1.217 100 33.82 2.96
12 1.167 100 32.41 3.09
12.5 1.120 100 31.11 3.21
13 1.077 100 29.91 3.34
13.5 1.037 100 28.81 3.47
14 1.000 100 27.78 3.60
14.5 0.966 100 26.82 3.73
15 0.933 100 25.93 3.86
15.5 0.903 100 25.09 3.99
16 0.875 100 24.31 4.11
16.5 0.848 100 23.57 4.24
17 0.824 100 22.88 4.37
17.5 0.800 100 22.22 4.50
18 0.778 100 21.60 4.63
18.5 0.757 100 21.02 4.76
19 0.737 100 20.47 4.89
19.5 0.718 100 19.94 5.01
20 0.700 100 19.44 5.14
Re: Mil-Dot Question
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wild_Man</div><div class="ubbcode-body">So what you are saying is:
subtension unit = range(yds) x mils / tgt size(")
with "su" to be determined for each power by measuring mils at a known range and target size?
Interesting concept. </div></div>
Exactly! But most importantly it can be done with any multi-stadia reticle as long as the stadia gaps repeat their subtension. A ballistic or BDC reticle requires 1 more calc.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wild_Man</div><div class="ubbcode-body">So what you are saying is:
subtension unit = range(yds) x mils / tgt size(")
with "su" to be determined for each power by measuring mils at a known range and target size?
Interesting concept. </div></div>
Exactly! But most importantly it can be done with any multi-stadia reticle as long as the stadia gaps repeat their subtension. A ballistic or BDC reticle requires 1 more calc.
Re: Mil-Dot Question
Magnification is inversely proportional to subtension (as long as the power ring is calibrate correctly). I'm actually working with a 4-16x Center Point optic, since it's getting some good reviews here and there on the Internet. The mil system is nice as it has 7 mil dots in each quadrant. They're supposed to be cald. for 10x, which means that at 16 they should be 2.25 IPHY between dots (10/16x3.6=2.25). And it is exactly that measurement, believe it or not. I would much rather use this optic at that power for downrange zeroing and rangefinding, as the power ring has a "zero stop" if u will at the upper power, ensuring that i'm at the same power (and consequently subtension) every time.
I almost always use my multi-stadia reticles at the optics highest power for rangefinding and downrange zeroing.
Magnification is inversely proportional to subtension (as long as the power ring is calibrate correctly). I'm actually working with a 4-16x Center Point optic, since it's getting some good reviews here and there on the Internet. The mil system is nice as it has 7 mil dots in each quadrant. They're supposed to be cald. for 10x, which means that at 16 they should be 2.25 IPHY between dots (10/16x3.6=2.25). And it is exactly that measurement, believe it or not. I would much rather use this optic at that power for downrange zeroing and rangefinding, as the power ring has a "zero stop" if u will at the upper power, ensuring that i'm at the same power (and consequently subtension) every time.
I almost always use my multi-stadia reticles at the optics highest power for rangefinding and downrange zeroing.
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