Rifle Scopes Judge size using mils

[droop]

Ok i'm new to the idea of utilizing mildots and have a few questions. Pardon me If the answers are right in front of me and I just missed them. I understand now about using mildots to find the range of a target with the target size, (the rule of using inches and 27.8 as a constant makes the most sense to me.)

However, what i'm trying to figure out is can size be judged using mils under certain parameters that remain constant from scope to scope. For instance under 4 power magnification, one mill dot is equal to X ft/inches or similar unit.

Keep in mind I do not have a mildot scope or i would try to judge it myself.
I understand that there would be a great deal of room for error of the shooters judgment but a general formula would be nice when there are no recognizable markings to compare size with.

 

[High Binder]

Re: Judge size using mils

Mildot master

 

[Lindy]

Re: Judge size using mils

If you have a second focal-plane scope, remember that at the magnification at which the reticle is correct, one mil covers 3.6 inches per hundred yards of range.

Most - but not all - SFP scopes are set up to range at maximum power. There is no advantage I can think of to using a lower power.

So, you just need to modify the ranging formula to solve for target size. That will give you:

<div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>
range in yards * image size (mils)
size (inches) = ----------------------------------
27.77
</pre></div></div>

As the previous poster noted, the easiest way to do that calculation is with a Mildot Master.

 

[sscoyote]

Re: Judge size using mils

U can adapt the mil-ranging formula for any reticle subtension. Recently we measured the size of a target at 1000 yds. using "reverse milling" by calculating the reticle subtension on a 500 yd. target that measured 9.25". The mil-dot was calibrated ofr something like 14x, and we elected to use the optic at it's highest power (32) for measuring purposes. The target measured 19.2" and we calcd. it at 18.9.

 

[Lindy]

Re: Judge size using mils

One thing about your original question which may not be obvious to you.

If you know the distance, you can calculate the size, as I noted above.

If you know the size, you can calculate the distance.

If you know neither the size nor the distance, you're going to have to rely on some other way of obtaining the distance/size, because without knowing one of those, you cannot calculate the other by measuring it with the scope.

 

[Ratbert]

Re: Judge size using mils

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">

If you know neither the size nor the distance, you're going to have to rely on some other way of obtaining the distance/size, because without knowing one of those, you cannot calculate the other by measuring it with the scope.
</div></div>

Which is why many data books will contain charts listing "normal" size of "common" objects. Such as the height/width of a "normal" door frame, window, or tractor-trailer tire. If you don't know if your target is 6'4" or 5'6" then you can just measure the door frame he's standing in front of and get your distance from that.

 

[sscoyote]

Re: Judge size using mils

I've been running 3-5% accuracy out to 500-600 yds. using many different reticles on antelope and a few deer, as i see them often while coyote hunting during the winter.

 

[hydro556]

Re: Judge size using mils

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lindy</div><div class="ubbcode-body">One thing about your original question which may not be obvious to you.

If you know the distance, you can calculate the size, as I noted above.

If you know the size, you can calculate the distance.

If you know neither the size nor the distance, you're going to have to rely on some other way of obtaining the distance/size, because without knowing one of those, you cannot calculate the other by measuring it with the scope.
</div></div>
Thanks for stating that so clearly. I have been trying my hand at learning to range with the P4F in my PMII. It is quickly humbling and makes me think my LRF was money well spent.

I know that if batteries die, I may as well not have it, to be clear.