Adjusting Drop chart to real World Results

Discussion in 'Long Range Hunting & Shooting' started by scsims, Nov 7, 2011.

  1. scsims

    scsims Well-Known Member

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    My ballistics software doesn't exactly follow the same amount of drop as I'm seeing when shooting in the field. I'm shooting 168gr SMKs at 2750 fps. I've only shot out to 500 yards and the MOA table is off, what's the best way to adjust the software to show my field results?
     
  2. WildRose

    WildRose Well-Known Member

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    Adjusting the BC and/or MV ususally solves it.

    There's a couple of other threads on the same subject from the last week or so, so you might be best served by scrolling down and reading them.
     

  3. 4xforfun

    4xforfun Well-Known Member

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    Question for you. Do the environmental paramaters (temp, alt, baro...ect...) on the computer program you used match your "real world" shooting weather? That can be a biggy, depending on when/where you did your shooting.

    If they are the same, or close, then what Wildrose said......MV or BC...sometimes a little of each. Sometimes I mess with the altitude, also.

    The further out you can actually shoot, the eiser it is to tell the difference and the better you can tweak the numbers to match real world.
     
  4. scsims

    scsims Well-Known Member

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    Yeah the environmental data is good, so if I have the 500 yard MOA adjustment of 10.5 and I set the software to reflect that will all the ranges under that be accurate with the software?
     
  5. WildRose

    WildRose Well-Known Member

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    Not necessarily. There are too many variables which no ballistics program on the market can control or solve for.

    Once you have two or three ranges recorded data matching what your program spits out, you should however be close enough for hunting purposes.
     
  6. retiredcpo

    retiredcpo Well-Known Member

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    I also found most software to be off alittle form what real shooting told me
    What I do is use the software to get me real close then I record my actual numbers in excell and create my own drop charts to number I have verified by shooting
    Most software is real close
    retiredcpo
     
  7. RDM416

    RDM416 Well-Known Member

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    Have you checked you scope to verify it actually moves 1 moa when you dial 1 moa? The adjustments on scopes (even good ones) are not always exactly on.

    You did not mention if you have a chronograph or if you are using data book velocities?? How many shots are you taking your average from if you are using a chrono?

    Make sure you have your "sight height" set accurately. Do not guess, measure it.

    Use Brian Litz G7 BC rather than the G1 BC if your program supports it.

    I used to always struggle getting my programs to match up with the real world. I have since learned to make sure I have ALL the data in my program correct, no guesswork on environmental conditions and other parameters. Now my ballistic program ("Shooter" for android on my phone) is usually dead on or very close. If you are certain you have everything else right, as others have said you can play around with the BC and MV to get your results match as close as possible.

    How much are your actual results off from your range results? Are you shooting groups and averaging the group or just one or two shots at each range?
     
  8. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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  9. Alan Griffith

    Alan Griffith Well-Known Member

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    Scott,

    You never did say how far off your drops were.

    This past summer, I discovered something about my Shooter program on my DROID that had me pulling my hair. I won't go into details but it had to do with station barometric pressure vs standard pressure for a known altitude. Put me 2 MOA off. I started to play the numbers with the BC or velocity and it just didn't jive. That's when I went back to my input values and discovered "my" GIGO mistake; Garbage In, Garbage out!

    Alan
     
  10. Greyfox

    Greyfox Well-Known Member

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    I believe that it is quite common to have to make corrections for a particular rifle load combo when working with standard ballistic programs. I have had good success with the calculator on the Best of the West site. I am sure there are other programs that do this, but the program provides for the correction of the actual impact points at long range and then enables you to determine a very precise ballistics chart. It then will provide an output that show either a "true velocity", or a "true ballistic coefficient". You can choose which one. My personal approach is to get the true ballistic coefficient since I am pretty confident in my velocity readings that I confirm on multiple set ups. I can then plug my true ballistic coefficient into my I phone FTE calculator which then will coincide and produce the same ballistic info, or use the data to make a ballistic turret.
     
  11. scsims

    scsims Well-Known Member

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    I'm off by about .5 moa.
     
  12. Alan Griffith

    Alan Griffith Well-Known Member

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    Scott,

    Could that be as simple a fix as adjusting your zero .5 moa?

    Alan