Question for Dave King

Discussion in 'The Basics, Starting Out' started by GEG, Apr 14, 2002.

  1. GEG

    GEG Well-Known Member

    Messages:
    98
    Joined:
    Feb 22, 2002
    Thank you Dave for explaining how to determine how many 1/4 min.clicks to turn
    to at the different yards. I hope you
    can explain it just as easy when mil
    dots are used! My scope has 10 mils
    total of hold over on the down vertical
    portion of the reticle graduated in 1/2
    mil marks. "All" I know is that a mil is
    equal to 3.6 inch's at 100 yards, after that
    I am completely lost. My scope has 1/4 min. clicks that total 50 from top to bottom
    also, so that means 25 can be used for more up. Can you please eplain how I am
    to know which of the 20 hold points I am
    to use and at what distance? Thanks very
    much for your time. GEG
     
  2. Dave King

    Dave King Well-Known Member

    Messages:
    2,362
    Joined:
    May 3, 2001
    Okay, I'll give it a shot (so to speak).

    A Mil (milliradian) is an angular measurement equal to 3.6 inches at 100 yards, this you already know. The part of this little puzzle that you need is that 1 Mil in also 3.44 MOA (or thereabouts). (Here's the math, 1 MOA = 1.047 inches at 100 yards, 3.44 (MOA) X 1.047 (Inches) = 3.60168 inches at 100 yards)


    Now your problem is solved, if you zero at the exact center crosshair and shoot using the first dot down you've essentially just "cranked up" 3.44 MOA. Shoot using the second dot down and you're 6.88 MOA up, 3rd is 10.32, 4th is 13.76, 5th is 17.2 MOA.

    You state you have .5 Mil marks also so this value is 1.61 MOA


    I'm careful about using the Mil dots for aiming points. If you get excited you may forget which Dot is the "Zero Dot" and really bugger things up. I nearly always use the center as zero and use the lower Dots for holdover marks.

    Here's a scenario for a "standard" set of 308 Win data using an system like your's as an example.

    Here's what I use as a "Base" set of "Come-Ups" (in MOA) for 200 through 800 yards.

    2, 3, 3.5, 3.5, 4, 4.5, 5

    To use this data on a Mil dot scope with .5 Mil marks, I'd do this.

    I'd "Zero" the rifle on the center crosshair.

    Then I'd adjust the elevation UP 1.5 MOA as this would allow me to use the first .5 Mil up mark (1.6 MOA) as my 100 yard Point-Of-Aim (POA).

    My crosshair would become my 200 yard POA.

    The first full Mil Dot down as my 300 yard POA. (My "standard" set of Come-Ups required 5 MOA for 300 yards and this fist Dot down is now at (1.5 "clicked up" + 3.44 "Hold Over" = 4.94 MOA) so I'm right on for 300 yards.)

    My next full Mil Dot down is another 3.44 MOA and I need 3.5 MOA for my next "Come-up" so the 400 yard POA is Mil Dot #2 Down. (The previous 4.94 MOA + 3.44 MOA more = 8.38 MOA and the projected "standard" amount is 8.5 MOA so we're very close.)

    Use the next (3rd) Dot down as 500 yards. It's an additional 3.44 and the "standard" Come-Up from 400 yards to 500 yards is 3.5 so we're still tracking well. (The previous 8.38 + 3.44 more = 11.82 MOA and the predicted amount is 12 MOA.)

    I'd imagine this will either clear things up fairly well or really confuse you.


    If you post your actual "Drop Chart" data we can try to match your "actual" data to the Mil marks rather than using the 308 Win stuff.
     

  3. GEG

    GEG Well-Known Member

    Messages:
    98
    Joined:
    Feb 22, 2002
    WOW!!! I wish I would have ask years ago
    instead of just guessing. I now get it
    and think I can even explain it to some one else! WOW!!! I thank you for your time
    and I will now use this info in my Hunter Ed classes if the question comes up. Thanks
    again. GEG