I just got a Mil-Dot for the first time and have a hold over question. I have my 7mm STW sighted in for 300 yards so it is 2.5 inches high at 100 yards. Now if I shoot at 100 yards with my first dot I hit the paper 5.5 inches high. So here is my question can I use the first Mildot at 500 yards and the second dot at 600 yards? I am shooting 140 Nosler Accubonds at 3430 FPS.

1 mil is 3.438 minutes of angle. You need to work your holdoffs from that number.

Round that number to 3.5 moa because that's as accurate as you'll need to be.

Next, sight your rifle for 100 yards.
Compute the drop in moa at further ranges.

Example;
My 308 sighted at 100 yards is 9.75 moa low at 500 yards.
As a mil hold I would use the top of the 3rd mil dot as my aim point and be assured of a first round hit.

9.75 / 3.5 = 2.79 moa.
Top of the 3rd dot is 3moa. Close enough.

Log on to JBM ballistics page, and type all your data in (temp.,elev.,MV,etc.), set your 100yd. zero@ 2.5" and then use MILS in the box that shows your trajectory drop. This will give you mill holds up to the 5 mil max of your scope. Then just shoot to confirm. Theyre usually pretty close. Hope it helps.

My first suggestion is to locate the thread in the optics section named "Is it a mistake". This is a good discussion on the Mil-Dot reticle by several members, each having different perspectives. The actual distance between the dots i.e. 1 Mil is 3.6 MOA or 3.6"@ 100yds, 7.2"@ 200yds ect...

Now unless you have a ballistics program, the best way to work this out is at the range, but I ran it through a program based on the info you provided. Now,if you're zeroed at 300yds and you're hitting the target 2.5" high at 100yds then 2.5"@ 100yds is 2.5 MOA. So your come-down from your 300yd zero would be 2.5 MOA or 10 clicks on the elevation turret if it's a 1/4 increments. Now you could also use the mil-dot reticle and change your point of aim. To do this, you would divide your come-down, 2.5 MOA by 3.6 which equals .70 Mil. So your POA would be .70 MIls low of center target or .30 Mils from the first upper dot with ref. to the cross hairs. Make sense? Now, to determine other come-ups and downs you would actually have to go to a 200, 400, 500 yd target and record where the bullet hits the target in inches from center. Example, if you shooting at a 200yd target and you hit it approximayely 3" high, calculate your MOA, 3"/ 2= 1.5 MOA or 6 clks down or using the mil-dot reticle your POA would be 1.5/ 3.6= .4 Mils low of center. Give this some thought. Below are some come-down and ups based on your info. Try them using the elevation turret.

Zero 300 yds. Set the turret to zero and lock down.
100 yd come-down= 2.5MOA or 10 clks down
200 yd come down= 1.5MOA or 6 clks down
400 yd come-up = 1.8MOA or 6 or 7 clks up
500 yd come-up = 3.8MOA or 15.2 clks up

These are estimated based on the limited info I have from your message. All these C-ps and downs start at your zero. Good luck!

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Expeience the best, Judge the rest!!

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Experience the best, Judge the rest!!

Antslayer, the U.S. Army uses the 3.6 MOA reticle where the U.S. Marine Corps uses a 3.438 MOA reticle. It's recommended to use the mean which is 3.5 MOA. There are numerous web sites you may want to review that explain this as well as the Book,
"The Ultimate Sniper" Whether he uses the 3.438, 3.5, or 3.6, the the infomation is correct. Besides, the differences would be insignificant in a hunting situation. Math doesn't lie. :^)

The Mil-Dot
The "Mil" in "Mil-Dot" does not stand for "Military"; it stands for "milliradian." The radian is a unitless measure which is equivalent, in use, to degrees. It tells you how far around a circle you have gone. 2 PI radians = 360 degrees. Using 3.14 as the value of PI, 6.28 radians take you all the way around a circle. Using a cartesian coordinate system, you can use "x"- and "y"-values to define any point on the plane. Radians are used in a coordinate system called "polar coordinates." A point on the plane is defined, in the polar coordinate system, using the radian and the radius. The radian defines the amount of rotation and the radius gives the distance from the origin (in a negative or positive direction).

ANYWAY, the radian is another measurement of rotation (the degree/minute/second-system being the first). This is the system used in the mil-dot reticle. We use the same equation that we used before, but, instead of your calculator being in "degree" mode, switch it to "radian" mode. One milliradian = 1/1000 (.001) radians. So, type .001 into your calculator and hit the "tangent" button. Then multiply this by "distance to the target." Finally, multiply this by 36 to get inches subtended at the given distance. With the calculator in "radian" mode, type:
tangent(.001)*100*36 = 3.6000012" Where the confusion may lie is that 1 MOA@100 yds is acutually = to 1.047" not 1". So if you calculated it using the USMC reticle which is = to 3.438, 3.438x1.047=3.6"

So, one milliradian is just over 3.6 inches at 100 yards. If we extrapolate, two milliradians equal about 6 feet at one-thousand yards. You'll see the importance of this, shortly.
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Experience the best, Judge the rest!!

[ 10-08-2004: Message edited by: PracTac ]

__________________
Experience the best, Judge the rest!!

Thanks everyone I think I will have to work on my math. [img]images/icons/shocked.gif[/img] I guess after the wedding this weekend I will Have to do some long Range practice with the new scope and try and figure things out. [img]images/icons/grin.gif[/img]