Mil-Dot Hold Over Question

Discussion in 'Long Range Scopes and Other Optics' started by dakor, Oct 8, 2004.

  1. dakor

    dakor Well-Known Member

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    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.
     
  2. Mike in Texas

    Mike in Texas Well-Known Member

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    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.

    Make sense?

    Good shooting..........................
     

  3. JD

    JD Active Member

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    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.
     
  4. Steve Douglass

    Steve Douglass Well-Known Member

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    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!

    --------------------------------------------
    Expeience the best, Judge the rest!!
     
  5. Guest

    Guest Guest

    dakor-- You will be low at 500 yards,(2" or a little more) and you will be more than 4 inches high at 600 yards, depending on atmospheric conditions.

    Prac Tac-- 1 mil IS NOT 3.6 MOA

    [ 10-09-2004: Message edited by: Antslayer ]
     
  6. Steve Douglass

    Steve Douglass Well-Known Member

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    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.
    --------------------------------------------

    Experience the best, Judge the rest!!

    [ 10-08-2004: Message edited by: PracTac ]
     
  7. dakor

    dakor Well-Known Member

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    Thanks everyone I think I will have to work on my math. [​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]
     
  8. Ian M

    Ian M Well-Known Member

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    PracTac
    Thank you for your concise explanation - wish I could do that since I use this stuff all the time. Bottom line is that some individuals (military and L.E. obviously) need this info because it could be life or death, theirs or someone elses.

    This is not a tactical site, nor does it serve any purpose for actual tactical shooters. We are devoted to Long Range Hunting - membership ranges from guys who have a fortune invested in toys to guys who are lookiing to make their first purchase of a mildot scope.

    Why do hunters possible need dots? One reason, for a very small number of mildot owners, is to ensure a clean kill if their lasers crap out. That is if they can remember the basic numbers and proceedure involved to come to a reasonable range estimation.

    Also mildot scopes can give us five additional hold-off points in the field of view, IF we know where in hell they relate to the trajectory of our bullet.

    If I was answering the original question I would suggest that Dakor shoot to find out where his bullets strike in relationship to the various dots- there are so many variables involved that I believe shooting is the best way to learn where to hold. Some guys do not have access to big ranges, or safe places to shoot long enough to do that, so computer projections will have to suffice till they do some shooting.

    This site works because we try to help each other, sharing info whether it is pretty basic stuff or very involved. We are fortunate to have some great guys here, guys like Bounty Hunter who I have never met but enjoy each of his posts.

    Len's rules regarding being civil and courteous are probably as important as the LR stuff being discussed. I will use my Leica 1200 every time, but there is always the chance that its battery will go and knowing how to work the dots might give me a more confident range estimation than just guessing.

    I appreciate your taking the time to explain that mil stuff, it served as a refresher to me even tho I have read it and been taught it many times previously.
     
  9. Guest

    Guest Guest

    Practac-- You explain Mil dots like John Kerry explains his position on Iraq.

    So there is NO CONFUSION, LISTEN UP.

    Both "Mil Radians and "Minutes of Angle" are systems of angular measurement.

    There are 6283 Mil Radians in a circle.

    There are 21,600 "Minutes" in a circle.

    21,600 divided by 6283 equals 3.4378481

    One 'Mil' equals 3.437841 'Minutes' ----Not 3.6

    Just because the Army chooses to build a reticle that does not conform to the known and defined system of angular measurement, does not change the system or the definitions.

    Like you said, "The math does'nt lie."

    Most scopes come with True Mil spacing, and Schmidt & Bender, U.S. Optics and Nightforce offer Models with 1/10th Mil clicks. You want to induce .162 Mils of error right from the start? Ridiculous.

    If that error is so inconsequential, why do the best scope manufacturers offer that level of click resolution? Try hitting a target at 1,000 yards in a hunting situation with a 4.7 percent ranging error, or holdover error, back to the real world. [​IMG]
     
  10. sscoyote

    sscoyote Well-Known Member

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    Something else u may wanna consider is the location of that reticle-- if it's in the 2nd focal plane of a variable power scope (ranging must be done at a certain magnification), then by changing the magnification the mil spacing changes also-- this allows for a lot of flexibilty in downrange zeroing. But then ranging also changes as well. Just another wrench in the works-- got enuf of those yet??
     
  11. Pete Lincoln

    Pete Lincoln Well-Known Member

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    Now if you Americans would just stick to miliradians you would find the calculations a whole lot easier. you range in meters and kilometers (well your military does) then you fart about reconing back to fractions of inches ior MOA. stay in miliradians and 10th of miliradians. 1/10 miliradian = 1 cm @100m. I have quick hold overs noted (and verified) for each dot in my scope, by holding a little high or low i can hit a mans torsoe every time out to distances way out. the dots as reference marks for hold overs (and unders) are good for quick snap shooting, If possible and time allows i always use the adjustable turrets.
    Guy do your selves a favour, convert to meters and miliradians, work out your trajectory in meters, and your hold overs in miliradians,, it is by far the simpler system,
    the late Bruce Robinson once wrote me "Pete i totaly agree with you, but don't tell anybody " well Bruce knows i can't keep my mouth shut when preaching on range estimation and the advantages of sticking to miliradians and meters. Pete
     
  12. Steve Douglass

    Steve Douglass Well-Known Member

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    Ian M, I agree with you completely and I do understand that this is not a tactical site. I joined this site because it's a LRH site and was searching info that could help in that arena. I appreciate your comments for their clarity and civility.

    Antslayer, first of all, I'm very aware of the math, but the reference to the 3.6 MOA was due to the fact that is 1 Mil= 3.6" because 3.438(1.047)=3.6@ 100yds and 1 MOA= 1" @ 100yds then doesn't 3.6"= 3.6MOA? What's disappointing is that rather than asking for an explanation there are those who are more concerned with trying to prove a point. I was merely providing some information to dakor, not looking for a debate on the subject. Oh, and I'll ignore the comment about you comparing my explanation to John Kerry's explanation on Iraq. I posted the thread "Mil-dot debate", take a look at it.

    All I saw this weekend was a couple of Blacktail Does. One running away about two yds away and the other crossing the road.

    Steve Douglass (USMC)

    --------------------------------------------

    Experience the best, Judge the rest!!
     
  13. Jeff In TX

    Jeff In TX Well-Known Member

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    Peter Lincoln,

    Sorry, I've been off of Sniper Country and Sniper's Hide for a while.

    When did Bruce Robinson pass? I'm very sadden by the news, his Mil-Dot Master will live on forever in the hands of everyone who uses it. I last talked with Bruce in the April/May time frame. He was also a fantastic person to have dinner and hang out with if you ever got the chance which I did on a number of occasions. I always kidded him that he never let go and say good-bye to the 60's or his Leatherman.

    His wife LouAnn was very pleasant to talk with on the phone.

    Again, I'm sorry to hear that he passed and even more sorry, I've heard about it this late.

    What a great guy! [​IMG]

    [ 10-11-2004: Message edited by: Jeff In TX ]
     
  14. sscoyote

    sscoyote Well-Known Member

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    Pete-- i like messing around with the system-- heck over here if u make a rule, the next thing that happens is someone trys to find a way to break it (sometimes i think that's the basis for technological inovation-- well, some that is).

    It is fun to play around with ranging and ballistic reticles tho. It definitely adds a world of flexibility to the system, and fun (for some).

    Hey how's the skiing over there by the way?-- used to go up to the Black Forest over there when i was a kid. That was the days of the lace up ski boots, and cable release bindings tho. Man i sure miss the brochen (spelling?) too.