What's a MilDot?

Princess

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Mar 6, 2014
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If a Mil is one miliradian, then shouldn't a MiDot be 3.6 inches at a hundred yards. I've noticed that some scope manufacturers market their products as having "MilDot Reticles" but the spacing of their mildots isn't even close to 3.6 inches, regardless of the level of magnification applied
 
A Mil-Dot is 1/1000th of a dot. They're very hard to see. That's why only snipers can use mil-dot scopes because of their great eyesight. :D

There are two types of adjustable scopes to think about, first-focal-plane reticle and second-focal-plane reticle.

On a first-focal-plane scope, the reticle appears to change size as the magnification is changed. On these scopes, the distance between the mil-dots at a given range will be constant. At 100 yards, it should be 3.6" or whatever the manufacturer specifies as the subtension since there are several slightly different values for a miliradian depending on who you ask.

On a second-focal-plane scope, there will be one specific magnification level where the subtension matches the specification. On most scopes, it's the highest magnification level. I've got 3 mil-dot scopes, all 2nd focal plane, and all of them are correct at the right magnification.

You may need to be a little more specific in your question because if you have a scope where it's not the correct subtension at the specified magnification, the manufacturer should fix it for you.

Matt
 
Thanks for the input.
Matt, you mentioned "You may need to be a little more specific in your question" Probably a good idea.
Every second focal plane MilDot reticle scope I have ever used provides a one mil (3.6 inches) spacing of the dots at 100 yards when the scope is on its highest power level. I have come to understand that there are some second focal plane "MilDot" scopes that use some other dot spacing factor and that, regardless of what power the scope might be set at, there is never one mil spacing for the dots at 100 yards. Perhaps I'm obsessed but I can't understand how a scope manufacturer can call their recticle "MilDot" when the spacing of the dots in their scopes don't match the miliradian formula.
 
Princess, if the 2nd FP optic you're using has the mil calibrated for a power lower than the highest, then at some power it should be exactly 3.6 IPHY. It can be measured easily enough. The 2 MD optics I have where the milliradian is setup for lower powers are dead on the nose correct--even a Centerpoint 4-16X (10X). I don't apply mil-ranging at the calibrated power though--I go straight to the optic's highest power and simply use a different factor in the formula.
 
Once familiar with mil dot, I prefer mil based scopes with hashes at mil and half mil, that are finer for ranging siting etc.
 
It likewise annoys me that the term is used so universally and that no standard truly exists by which one scope can be accurately compared with another. You know - our (6.5 - 20) "MilDot" reticle spacing is one mil at 10 power, the other guy's (6.5 - 20) provides one mil at 20 power. But I'll get over it :D
 
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Also, some dots are ovals (not round) 1 mil high, yet 2 mils wide, Then the (dots) are placed 5 mils apart. All of this aids in "Mil-Dot Ranging". First Focal Plane scopes will allow you to do this at all powers.

Paul
 
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