Thread: Determining mil value at different magnification??

Just found this in a comment on a review of my scope on the vortex site.

"If you have a variable power scope and the calibration (cal.) for the subtensions of the reticle is say 14x on a 6.5-20 power scope you can determine the hash mark spacing at say 6.5x, 8x and 20x. by using the following formula.
Divide the cal. (14x) by the desired power, say 6.5x or 20x and then multiply the cal. subtension size by this answer. You can now make a chart for hold over or even ranging.
Here we go. 14x/20x=.7, 14x/8x=1.75 and so on. Now take the answer, say .7 for the 20x. Multiply the answer against the cal. subtension size.
If the subtension, (mil-dot) spacing is 3.6" at 14x it will be 3.6 x .7= 2.5" @20x. 3.6" x 1.75= 6.3" @8X and 3.6 x 2.1=7.56" @6.5x"

So ive just calculated that on 20x 1 mil spacing will equate to 2.5" @100yds, so 2.5 divided by 1.047 = 2.387 MOA (on 20x), so the top of the bottom post (5 mil) gives me 11.93 MOA, so say 12 moa.

Where as on 14x that same point on reticle gives me just shy of 17.5moa.

So thats what i wanted to know. I'll double check by actual shooting at the range anyway, as the 20x may not be a true 20x eh.

Thanks for the help guys.