Help - Figureing out ballastic issues

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  • StoneHendge
    Chieftain
    • May 2016
    • 2009

    #16
    Corrected:

    Shooter puts 700 yds at -5.7 using the G7 .255

    The -5.4 from JBM is meaningless. All you care about is the actual air pressure - i.e. Station pressure. Barometric pressure readings can be adjusted to what they would be at sea level. In those instances, altitude adjusts them back to absolute pressure. My guess is that with the 5.4, the program is adjusting a 25.3 sea level pressure to what it would be at your altitude...

    Throwing that out, No output is really more than 0.1 mils off the mean. That's about 1/3 MOA on a 2 MOA target.....
    Attached Files
    Last edited by StoneHendge; 07-26-2017, 02:18 AM. Reason: corrected for angle
    Let's go Brandon!

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    • LRRPF52
      Super Moderator
      • Sep 2014
      • 8569

      #17
      Hornady has doppler radar data for that bullet in their program.

      Not sure how accurate it will be, but I would try that too.
      NRA Basic, Pistol, Rifle, Shotgun, RSO

      CCW, CQM, DM, Long Range Rifle Instructor

      6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

      www.AR15buildbox.com

      Comment

      • Klem
        Chieftain
        • Aug 2013
        • 3507

        #18
        They are all slightly different and are theoretical simulations anyway. None are likely to match exactly your gun in whatever conditions on the day. In your shoes I would shoot the 800yds (and at as many other ranges as I could) to get a feel for your ballistic curve. Then see which calculator is the closest match. Any of the estimations will get you on paper.

        I use Applied Ballistics on the Kestrel for careful shooting and Bullet Flight on the phone for quick and nasty calculations.

        Comment

        • Sticks
          Chieftain
          • Dec 2016
          • 1922

          #19
          Thank you everyone for their help on this.

          Trying to run before I've learned to walk properly.
          Sticks

          Catchy sig line here.

          Comment

          • LR1955
            Super Moderator
            • Mar 2011
            • 3355

            #20
            Originally posted by Sticks View Post
            Thank you everyone for their help on this.

            Trying to run before I've learned to walk properly.
            Sticks:

            Not really. You are simply falling into the technocrat trap. Not seeing the forest from the trees.

            Your target at 700 is two minutes. 14 inches. In your first post you said the differences between the various programs was .2 mils. .2 mils is about 3/4 of one minute. Any of your programs would give you a hit on the target somewhere and apparently all of them are pretty much center.

            If I were you and I couldn't get to that exact range and shoot that exact target, I would average the differences in your programs and use the result for an elevation. Just understand that no matter what one of the computer programs spits out, your particular rifle and ammo combination may not match up.

            If you go into your competition focused on the insignificant differences of elevation between your computer programs, you will not perform well. And most likely you will not be real happy about it.

            Use the computer for what it is worth, a pretty decent estimation of elevation. Then you are allowing yourself to focus on the important things that are more likely to bring success. Such as position, wind doping, the shot(s), and maybe even spotting trace through your optic which is quite possible with the Grendel.

            LR55

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            • JJA Guns
              Bloodstained
              • Nov 2017
              • 34

              #21
              There's no substitute for actually shooting your combo and adjusting your charts based on what results your getting in the field

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