Using Mil-Dots...am I missing something?

[Jason M]

Tonight for the past two hours I have been reading numerous sites about reading and utilizing mil dots in rifle scopes. After all the reading, I understand how they work and how you read them, I think. Let me state my confusion:

Lets say I am shooting my .243 at a 10" tall (at the shoulder) raccoon and I see it as .8 mils in the scope.

10"/36" = .278 yards tall

.278*1000 = 278

278/.8mils = ~ 347.5 yards to target

So I understand that part just fine and it seems quite handy, but then how do you determine the hold over height once you know the range? If I was zeroed at 200 yards, how do I determine my hold over height of the crosshair? I know I could just use a chart, but I want to understand the theory of this.

Thanks in advance to anyone who can help clear this up for me!

-Jason

 

[HorseSoldier]

You need a ballistics chart for the particular load you're using, converted into mils. As an example, 62 grain green tip out of a 14.5" barrel on a 100 yard zero has about 0.5 mils drop at 200, 1.2 mils drop at 300, and 2.2 mils drop at 400 (or so the cheater sheet I carry around claims).

There are a number of sources for this data free online, for either factory loads or computers where you can put in the mass, velocity and such for your particular handloads. You can also buy software from a number of companies that goes on your computer or PDA and allows more detailed numbers cooking, if you need that level of accuracy and precision (altitude and temp, etc.)

 

[Navy joe]

You have to know the trajectory of your load. So say you had a 300 yard zero that said come up 8 clicks of elevation from your 200yd, and a 400 that said come up 14 then you could raise your elevation say 12 clicks and be pretty close. You need to know YOUR rifle's muzzle velocity and the bullet's ballistic coefficient and then you can plug numbers into a ballistics program to get your come-ups. Or you can shoot at the various ranges and figure out come-ups by direct observation.

 

[sarduy]

So I understand that part just fine and it seems quite handy, but then how do you determine the hold over height once you know the range? If I was zeroed at 200 yards, how do I determine my hold over height of the crosshair? I know I could just use a chart, but I want to understand the theory of this.

Thanks in advance to anyone who can help clear this up for me!

-Jason

simple, "KNOW YOUR .243 BALLISTIC"

all you have to know is how many inches the .243 will drop at 100-200-300-400 yards...

so the raccoon is 10'' tall, same as = .8 mils in the scope
you have the rifle zeroed at 200 yards using 90gr bullets and they drop 10'' at 350 yards.

then you need hold-over 10'' to comensate the bullet's drop which is the same as .8 mils,

now if the bullet drop 20'' at 350 yards you need to hold 1.6 mils

same as if the bullet drops 5'' then you hold .4 mils.


same way you extimate the height of the raccoon, you need to do it to compensate for the drop of the bullet (but you need to know how many inches they drop at know distance, 100 200 300. . . .