Choosing an average elevation for my Leupold CDS

Discussion in 'Long Range Hunting & Shooting' started by Jeffpg, Dec 14, 2010.

  1. Jeffpg

    Jeffpg Well-Known Member

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    I have a new Leupold CDS scope for my Remington model 700 LSS in 300RUM. In putting together my ballistic info for the custom dial for my load, I am having trouble choosing an average elevation to set up for.

    Like most of us, I hunt all over the west for multiple species and can find myself at various elevation levels, but usually 5000 to 10,000 is within the range. My Leupold Rep tells me that the range of error is about 2000' on either side...in other words if I went with my original figure of 5000', I would be good from 3000 to 7000 feet, more or less. Of course the error will increase at longer ranges, and I haven't done my homework by consulting ballistic charts as to just how much the effect will be, but I'll get around to that soon. I'm sure some of you are well schooled on these numbers, or may have a good source of information to educate me.

    I feel the changes in elevation will have a minimal effect on my bullets trajectory except at longer ranges, and realize that it will fly flatter in the higher, thinner air. I also realize that having 2 different dials set up to compensate for extreme elevation changes would be best, but I want to see if I can make the one dial work across the board, even if it means learning to adjust for the extremes.

    I originally intended to go with 5000' elevation and 50 degrees temperature, but I am second guessing that after talking with a few fellow hunters/shooters. I am leaning a bit more towards 7500' currently. I'm sure some of you will share opinions that will challenge my thinking on this.

    My load consists of a 180 grain Swift Scirocco bullet with a .500 BC leaving the muzzle at 3250 fps.

    Thanks,
    Jeff
     
  2. horsefor4

    horsefor4 Well-Known Member

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    I had the same problem after doing some research I went with 6000' there is so little difference.Did 50 for temp. not perfect but gets you real close in good conditions.Hope that helps just check how much drop difference in elev.
     

  3. Don Ward

    Don Ward Well-Known Member

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    We build our personal dials at 7000' 30 deg for about everything from Idaho to New Mexico. Lots of customers have followed that lead with good results.

    2000' either way is about right for your load for stretching it out, but keep in mind that for medium range stuff (less than 500 yards) that window is bigger. 7000' 30 deg is basically identical (maybe a click) to 3000' 50 deg at 500 yards with your load.
     
  4. CLICKBANGBANG

    CLICKBANGBANG Well-Known Member

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    I just ordered mine and was thinking threw the same thing. I played with a ballistic calculator quite a bit. I found that at 500 yards with my set up, there is only an inch or two between moderate temp and elevation changes. I like to hunt around 7k ft but live at 55 ft elevation. Also summer shooting can have temps of 110 degrees. Last time I was out deer hunting it was 25 deg. So I picked a middle of the road number and if it is off a little, I will live with it. If one of them is way off, there only $60 for another.
     
  5. SBruce

    SBruce Well-Known Member

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    50 Degrees is probably a good average, at least it would be where I hunt deer/antelope in eastern Wyoming during October. Some years will be 60-70 degrees mid-day, others will be 25-35 mid-day. Temp doesn't vary with altitude a whole lot during the early season here. In other words, If I were to go northeast and climb 3000'......the mid-day temp doesn't change by more than about 10 degrees usually.

    You mention a 5 to 10K elevation...........I am assuming that the majority of your hunting is more likely around 6 to 8 K.??

    If I am assuming correctly, the 7K average will do you good for most situations.

    Based on the bullet/velocity you mentioned, a 2K elevation difference will theoretically yield a 3/4 to 1 minute change at 1000 yds, where a 20 degree temp change will theoretically yield a 1/4 to 1/2 minute change at 1000 yds.

    Again this is in theory and based on ballistic programs. But if you pick a realistic average, then you'll be able to figure a variance for higher/lower and colder/warmer than your average and allow for this when shooting.

    Best O Luck
     
  6. Buffalobob

    Buffalobob Writers Guild

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    Do your homework and make you a little chart of corrections to apply to your turret. Its not hard to do but does take an hour or so with a ballistics program.
     
  7. Jeffpg

    Jeffpg Well-Known Member

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    Hey guys, that's just the kind of info I was looking for and it's all helpful. I think we're all basically in agreement on this subject.

    If there is a such thing as a majority it probably is in the 6000 to 8000 ft. range. I am really liking Don's figures and at this point I don't see myself straying very far from them.

    I do get an extra dial thru Leupold's current Promo deal, but I want to use it for a different load, probably using either the 200 grain Nosler Accubond, or Berger's 210 grain VLD. Extra dials are currently running right at $100 each from Leupold.
     
  8. trueblue

    trueblue Well-Known Member

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    I would just have them make you an MOA turret, and then it won't matter. You can make a drop chart for whatever elevation you plan to hunt at, and tape it to your stock.
    If you are set on a yardage turret, I would base it on 7000', 30 degrees, 30 % humidity
     
  9. CLICKBANGBANG

    CLICKBANGBANG Well-Known Member

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    It comes with a MOA cap out of the box. Large marks at MOA, small marks at 1/4. And every third is numbered (0,3,6,9,12,0).

    One of the points of the yardage caps is to eliminate the cheat sheet and math between the range and optic. You won't be in a perfect world shooting and will have to judge windage and other variables. But with the base line yardage scale on the cap, your a little closer to being there quicker.
     
  10. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    I agree. Save your money and run a chart. It is not hard, and does not require any math.

    You might as well do hold over and have the same yardage limitations and accuracy. An easy to read MOA or IPHY turret will be much better in the long run, and allow you to change conditions and bullets any time you like. In my opinion all you are doing is limiting yourself with a yardage turret. They are a fad.

    Steve
     
  11. trueblue

    trueblue Well-Known Member

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    clickbang,
    i do not think that a yardage turret is that much faster than a MOA.
    I ran a huskemaw scope for awhile, when I was new to rifles , but since then have learned how to dial dope or holdover with an MOA reticle and see know advantage to a yardage turret. As far as I am concerned at this point I find it less flexible than just using a drop chart or pda for the conditions that I will be hunting in.
    To the OP, I say learn to use what you already have.