Thread: Mil-Dot reticle help pls clever fellas

OK fellas...

I'm having a real "thick" moment. The mil-dot reticle on a 2.5-15x second focal plane scope I am interested in has the specs shown on the attached image. My understanding is that mil-dot scopes are calibrated at 10x magnification to generate the correct holds on the ballistic solver. Milspec says so (I think) and is kind of backed by the fact that for many years military snipers used fixed 10x scopes. (I'm dredging the dark corners of my memory now so may be wrong.)

So in the image, at 15x power, the distance between two dot centres is 2.27 MOA, so 0.66 mrad. If it was calibrated at 15x, then this value should be 3.44 MOA or 1.00 mrad.

Seeing as how we have the values for 2.5x power, how do I calculate the 10x power value to confirm 10x calibration? I am expecting the distance between two dot centres at 10x power to be 3.44 MOA / 1.0 mrad.

Hope this makes sense. Any help that solves this will be much appreciated.

If its correct on 10x then 15x makes factor of 1.5 .
3.44 divided by 1.5 = 2.29 so from 15x to 10x it will be x 1.5 or 2.29 x 1.5= 3.44.

1mill /1.5 =.666 so yes looks like its true at 10x

Seems to work the other way as well.... ish.

2.5/10= 0.25
13.46x0.25=3.365

Don't really understand why the numbers we're generating aren't exact.

EG 2.27 vs 2.29 and 3.44 vs 3.365

Could be a number of things but Id guess the magnification values on the scope arnt exact. its quite common.

Agree – looks like rounding in the published magnification figures.
Calculates to be 2.554x to 15.13x
if the 1mil at 10x is spot on.

stick your meter ruler up at hundred yards/meters....or paper with known grid size on it....it SHOULD almost make working out whats what too easy....how many inch grids apart are your dots.....how many on each power setting....
D is really the only one you will use is it not???

There are 91.46 metres at 100 yards. Mils are 19cm at 100 metres. An moa @100m = 1.141"

Or just go FFP MRAD. Just saying...

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Originally Posted by Feral

Or just go FFP MRAD. Just saying...

I’ve got three.

But they aren’t right for this application. Horses for courses and all that.

Originally Posted by Woody

There are 91.46 metres at 100 yards. Mils are 19cm at 100 metres. An moa @100m = 1.141"

That’s a typo I assume @Woody. A mil is 10cm at 100m.

Originally Posted by Micky Duck

stick your meter ruler up at hundred yards/meters....or paper with known grid size on it....it SHOULD almost make working out whats what too easy....how many inch grids apart are your dots.....how many on each power setting....
D is really the only one you will use is it not???

Only works if you’ve already bought the scope, which I haven’t!

Okay... call me stupid but why have an mrad scope then convert it to moa ? Isn't the whole point of mrad to do away with moa... I thought mrad was supposed to be easier to use. Sure as hell don't look like it if you need to recalculate everything across from moa. And shouldn't the scope manual tell you which magnification is correct for 1mil at 100 mtr. Call me old school but I will stick to moa thanks....ok , rant over

Mil dot range finding.
…..................................

A full circle of 360degrees is 6283milliradians, or mils.

1mil @ 100m = 10cm
1mil @ 200m = 20cm
1mil @ 300m = 30cm
1mil @ 400m = 40cm
.
.
1mil @ 1000m = 100cm
1mil @ 1800m = 180cm

Quick calc, memorise this:

Height in cm / measured height in mils = distance in metres.

With the above you can determine at which precise setting your mil dot reticle actially measures mils.

And boys, lets forget about yards and inches.

Originally Posted by Cordite

Mil dot range finding.
…..................................

A full circle of 360degrees is 6283milliradians, or mils.

1mil @ 100m = 10cm
1mil @ 200m = 20cm
1mil @ 300m = 30cm
1mil @ 400m = 40cm
.
.
1mil @ 1000m = 100cm
1mil @ 1800m = 180cm

Quick calc, memorise this:

Height in cm / measured height in mils = distance in metres.

With the above you can determine at which precise setting your mil dot reticle actially measures mils.

And boys, lets forget about yards and inches.

I think the problem is he doesn't actually have the scope to test it out on a target to confirm those measurements on the reticule the easy way. Hence the nasa/particle physics level mathematics equations.

Originally Posted by Ftx325

I think the problem is he doesn't actually have the scope to test it out on a target to confirm those measurements on the reticule the easy way. Hence the nasa/particle physics level mathematics equations.

Yep. I just reckon Flyblown will trust his own measurements more than some factory blurb. So when he gets his scope he will just put a 10cm high or wide target up at 100m and zoom his scope till it coincides with one dot centre to dot centre measurement.

In the end, even if the factory leaflet is accurate, will the graduations printed on the scope zoom ring be correct? Literally only one way to know.

And forget MOA too.