J.Boyette
12-28-2008, 12:14 PM
Ok guys here we go. Go get your thinking caps on and come on back to read this.
What you need to have and know first off.
1. A calculator
2. A understanding of MOA
3. A understanding of the English unit of measure " inches, feet, yards"
4. A open mind and the ability to comprehend what you read.
5. A 100yd range
6. A computer printer
7. My e-mail address
Well here we go, A milradian is a unit of measure. To understand this unit of measure, and how it helps you is simple. All you need to do is know how big a MILRAD is at each 100yd lines you plan on ranging or shooting a target at.
http://i4.photobucket.com/albums/y117/RED68C/MilData.jpg
To do this at home, all you need to do is take the yard line value as in the 4 from 4 00yds an times it by 3.6" and you get the value for that distance. So now we know how big a Mil is at each distance. This information will inform you the shooter to the danger space, under shot, over shot, and point blank ranges of each ZERO you use. For more info on that, come see me :)
Using the reticule for unknown distance target ranging, or hold overs/unders is the same skill set. To range a target you need to know target size in width or height or mil size for advanced MILRAD usage.
How does this work?
Very simply, to find an unknown you need two pieces of the puzzle that are known correct? So for you to find an unknown distance to a target you need the following.
Mil size + Target size = distance to target.
Very simple.
So all you do is this.
Target size x 27.778 = a number / mil reading in the reticule = Target distance. That's it.
Let’s work on this. I have a 20”x40” target.
http://i4.photobucket.com/albums/y117/RED68C/target2.jpg
Now since I know how big a target is, all I need to do is line the target up in my reticle to get the Milrad reading.
http://i4.photobucket.com/albums/y117/RED68C/Ranging.jpg
The target to the right reads 1.2 Mil tall and .6 Mil wide. So lets use these numbers to get the range
Height:
40 inches x 27.778 = 1111.12
1111.12 / 1.2 Mil = 925.933 or 926yds ;)
Width:
20 inches x 27.778 = 555.56
555.56 / .6 Mil = 925.933 or 926yds ;)
WOW HOW DID THAT HAPPEN??????????????????????????????????? ;)
So tell me the range to the target on the left.
You should get a range of 555.56yds on both height and width.
Holds for Elevation, Windage
Now that we have covered the basic information and usage of the Mil-Dot reticle lets look at more advanced applications. We now know that a Mil-Dot reticle is a unit of angular measurement as is minute of angle. You can now use the ammunition ballistics that you have in MOA for hold-over’s, hold-under’s and windage to hit a target.
This is simple to do. Let’s use the Federal Gold Metal Match .308 win Ammunition (FGMM) with the 175 grain bullet as an example.
http://i4.photobucket.com/albums/y117/RED68C/holds1.jpg
Since we now have the ballistics that our rifle shoots. You need to pick a ZERO range for your scope. Then get the adjustment-ups or adjustment-downs from that MOA drop at that range to all the ranges you plan on using the Mil-Dots for hold-over’s and hold-under’s for.
The easiest way I have found to get the best ZERO setting on the scope is to look at your MOA from the closest range you will shoot at to the farthest. Most of us will use a 100 yard to 1000 yard ballistic sheet. For the Federal Gold Metal Match .308 win Ammunition our chart lists 37.37 MOA as the total drop. We take the 37.35 and divide it by3.43775. This gives us 10.86 Mils of total drop. Most reticules have 8 Mil-Dots with a 10 Milliradian over all size reticule. I have found that a ZERO SETTING between 600 yards and 700 yards works best for the FGMM .308win ammunition to cover 100yards to 1000 yards.
With that in mind, we will use the 675 yard data as the ZERO but you can use any MOA ZERO you would like. Some use a 400yd ZERO also to engage targets from 100 yards to 800 yards. The 675 yard data is at 18.75 MOA setting on the optic’s turrets from the 100yd ZERO. Now I need to find out what my adjustment-ups and adjustment -downs are from each range to 675 yards. If you subtract 675 yard MOA from 700 to 1000 yards you get your adjustment-ups. Then subtract the MOA at 100 to 500yds from the 675yd MOA for adjustment-downs.
You’re adjustment-up / down chart will look like this:
http://i4.photobucket.com/albums/y117/RED68C/holds2.jpg
Ok the fun part. We have the entire math we could ever want now. To make a hold-over / under we must take the adjustment-up/ down and divide it by 3.438 to get is value in Mil so we can use it with our reticule. Using the same data charts this is how it’s done.
I have my adjustment-downs and ups. All I have to do is take the adjustment-up or down number and divide it by 3.438 to get my mil-hold.
EXAMPLE:
400yard adjustment down from 675 yards = 11.21 MOA
11.21 / 3.438 = 3.26 Mil-Hold under 675yd ZERO
800yard adjustment up = 6.48 MOA
6.48 / 3.438 = 1.88 Mil-Hold over 675yd ZERO
To do the windage holds. All we have to do is take the true minute of angle wind drift and divide it by 3.438 and you get the wind hold in Mil.
http://i4.photobucket.com/albums/y117/RED68C/holds3.jpg
This is how your holds will look like when you need to use them.
Elevation Holds
http://i4.photobucket.com/albums/y117/RED68C/holds4.jpg
Windage Holds
http://i4.photobucket.com/albums/y117/RED68C/holds5.jpg
Hope this very short explanation helps. If you need any help, ask away. Or come to a How to use a Mil-Dot reticle class. Well worth it.
John
What you need to have and know first off.
1. A calculator
2. A understanding of MOA
3. A understanding of the English unit of measure " inches, feet, yards"
4. A open mind and the ability to comprehend what you read.
5. A 100yd range
6. A computer printer
7. My e-mail address
Well here we go, A milradian is a unit of measure. To understand this unit of measure, and how it helps you is simple. All you need to do is know how big a MILRAD is at each 100yd lines you plan on ranging or shooting a target at.
http://i4.photobucket.com/albums/y117/RED68C/MilData.jpg
To do this at home, all you need to do is take the yard line value as in the 4 from 4 00yds an times it by 3.6" and you get the value for that distance. So now we know how big a Mil is at each distance. This information will inform you the shooter to the danger space, under shot, over shot, and point blank ranges of each ZERO you use. For more info on that, come see me :)
Using the reticule for unknown distance target ranging, or hold overs/unders is the same skill set. To range a target you need to know target size in width or height or mil size for advanced MILRAD usage.
How does this work?
Very simply, to find an unknown you need two pieces of the puzzle that are known correct? So for you to find an unknown distance to a target you need the following.
Mil size + Target size = distance to target.
Very simple.
So all you do is this.
Target size x 27.778 = a number / mil reading in the reticule = Target distance. That's it.
Let’s work on this. I have a 20”x40” target.
http://i4.photobucket.com/albums/y117/RED68C/target2.jpg
Now since I know how big a target is, all I need to do is line the target up in my reticle to get the Milrad reading.
http://i4.photobucket.com/albums/y117/RED68C/Ranging.jpg
The target to the right reads 1.2 Mil tall and .6 Mil wide. So lets use these numbers to get the range
Height:
40 inches x 27.778 = 1111.12
1111.12 / 1.2 Mil = 925.933 or 926yds ;)
Width:
20 inches x 27.778 = 555.56
555.56 / .6 Mil = 925.933 or 926yds ;)
WOW HOW DID THAT HAPPEN??????????????????????????????????? ;)
So tell me the range to the target on the left.
You should get a range of 555.56yds on both height and width.
Holds for Elevation, Windage
Now that we have covered the basic information and usage of the Mil-Dot reticle lets look at more advanced applications. We now know that a Mil-Dot reticle is a unit of angular measurement as is minute of angle. You can now use the ammunition ballistics that you have in MOA for hold-over’s, hold-under’s and windage to hit a target.
This is simple to do. Let’s use the Federal Gold Metal Match .308 win Ammunition (FGMM) with the 175 grain bullet as an example.
http://i4.photobucket.com/albums/y117/RED68C/holds1.jpg
Since we now have the ballistics that our rifle shoots. You need to pick a ZERO range for your scope. Then get the adjustment-ups or adjustment-downs from that MOA drop at that range to all the ranges you plan on using the Mil-Dots for hold-over’s and hold-under’s for.
The easiest way I have found to get the best ZERO setting on the scope is to look at your MOA from the closest range you will shoot at to the farthest. Most of us will use a 100 yard to 1000 yard ballistic sheet. For the Federal Gold Metal Match .308 win Ammunition our chart lists 37.37 MOA as the total drop. We take the 37.35 and divide it by3.43775. This gives us 10.86 Mils of total drop. Most reticules have 8 Mil-Dots with a 10 Milliradian over all size reticule. I have found that a ZERO SETTING between 600 yards and 700 yards works best for the FGMM .308win ammunition to cover 100yards to 1000 yards.
With that in mind, we will use the 675 yard data as the ZERO but you can use any MOA ZERO you would like. Some use a 400yd ZERO also to engage targets from 100 yards to 800 yards. The 675 yard data is at 18.75 MOA setting on the optic’s turrets from the 100yd ZERO. Now I need to find out what my adjustment-ups and adjustment -downs are from each range to 675 yards. If you subtract 675 yard MOA from 700 to 1000 yards you get your adjustment-ups. Then subtract the MOA at 100 to 500yds from the 675yd MOA for adjustment-downs.
You’re adjustment-up / down chart will look like this:
http://i4.photobucket.com/albums/y117/RED68C/holds2.jpg
Ok the fun part. We have the entire math we could ever want now. To make a hold-over / under we must take the adjustment-up/ down and divide it by 3.438 to get is value in Mil so we can use it with our reticule. Using the same data charts this is how it’s done.
I have my adjustment-downs and ups. All I have to do is take the adjustment-up or down number and divide it by 3.438 to get my mil-hold.
EXAMPLE:
400yard adjustment down from 675 yards = 11.21 MOA
11.21 / 3.438 = 3.26 Mil-Hold under 675yd ZERO
800yard adjustment up = 6.48 MOA
6.48 / 3.438 = 1.88 Mil-Hold over 675yd ZERO
To do the windage holds. All we have to do is take the true minute of angle wind drift and divide it by 3.438 and you get the wind hold in Mil.
http://i4.photobucket.com/albums/y117/RED68C/holds3.jpg
This is how your holds will look like when you need to use them.
Elevation Holds
http://i4.photobucket.com/albums/y117/RED68C/holds4.jpg
Windage Holds
http://i4.photobucket.com/albums/y117/RED68C/holds5.jpg
Hope this very short explanation helps. If you need any help, ask away. Or come to a How to use a Mil-Dot reticle class. Well worth it.
John