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Vortex Razor HD scope not tracking true

Discussion in 'Shooting Chat' started by Jcann, Oct 2, 2018.

  1. Jcann

    Jcann Sharpshooter

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    Well, I'm one of the lucky ones. A couple weeks ago while out shooting I noticed something was amiss between my ballistic app and actual field data.

    At 455 yards my ballistic app gave me 2.0 mils but actual mils needed were 1.8
    1.8/2.0 = 0.90
    At 910 yards my ballistic app gave me 6.1 mils but actual mils needed were 5.49
    5.49/6.1 = 0.90

    So I have a 10% error in my scopes tracking. I went into the app and changed the elevation and windage correction factor to 0.9. Hopefully this will correct the problem for my hunt.

    It's my fault for not checking the tracking on the scope first. After my hunt I will run a box test and a tall target test before I send it off to Vortex.

    A really nice guy on Long Range Hunting forums who runs a ballistic software company checked all my data and set me up with a custom ballistic chart for my hunt. Many thanks to him for his help.
     
    dennishoddy likes this.
  2. doctorjj

    doctorjj Sharpshooter

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    Have you chrono’d your load?
     
  3. Jcann

    Jcann Sharpshooter

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    Yes, three times in the last four weeks using a Magnetospeed. To make up for the difference in muzzle velocity I would have to input a speed of over 3,050 fps. I can’t get enough powder in a 7wsm and 180 gr bullet to make that happen without blowing something up.

    I know most change velocity in their ballistic app’s to match field data but 3,050 fps is ridiculous. The app was nuts on for my sons rifle.
     
    Last edited: Oct 2, 2018
  4. doctorjj

    doctorjj Sharpshooter

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    Is this a Gen 2 scope?
     
  5. Jcann

    Jcann Sharpshooter

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    No, it’s a Gen 1
     
  6. swampratt

    swampratt Sharpshooter

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    Bullets have different BC based on velocity. say 2100-2800fps it could have one BC and 2800-3300 could have another.
    Then below 2100 could have another BC.

    I do not rely on apps, well for one I do not have a cell phone or lap top.
    And for knowing exactly where the shot will land takes a little walking and a little shooting.

    I use a very tall cardboard box I set it out to my max distance I will be shooting.
    I place an X on the target near the top of the box and zero the scope so I get hits there at 100 yards.
    Or 2" high if you wish to be 2" high or whatever at 100.

    Then step back to 200 yards and shoot while aiming at the same spot you aimed at before.
    Notice the drop.
    Then 300 yards notice the drop is even more.

    Now you need to steady rest the rifle at 200 and 300 and dial in the scope yards and set it up so the center of the crosshairs are at the aim point the X now adjust the clicks down to where the bullet landed. count the clicks.. or if you are shooting by holding over and using the mil dots or other lines.. notice what line or dot you need to use.

    My scopes are second focal plane so the scope power will change where the mil dots are on at the target.
    The dope on one of my rifles in the below picture.
    Notice the dot . above the 18 and one above the 12 that is exactly where i must line up my scope power setting against the dot on the scope tube.
    No more apps. just look at the side of the gun. The one below is my .223 axis with 55 v max.
    001.JPG
     
  7. Jcann

    Jcann Sharpshooter

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    Yes I know, I’ve been in the LR game long enough and try to work field ballistic data. BC does not explain the .2 mil difference at 455 yards (that’s a little over 5”). My sons 910 yard shots were based only on the shooter app. It was 24.4 moa and we used the publish Hornady BC. Don’t sale the apps short, I’ve found mine to be pretty darn close most of the time. It was nuts on last year out to 845 yards.
     
  8. doctorjj

    doctorjj Sharpshooter

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    How fast was it those times you did chrono it? And plenty of guys getting over 3000 FPS with 180gr in 7wsm.
     
  9. Jcann

    Jcann Sharpshooter

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    I've run this same load since day one with this rifle. It has slowed down from about 2984 to around 2930 fps with 65.8 grains of H1000. Looking at my archived series from my magnetospeed my min was 2914 and max was 2930 (this was a 10 shot series). These were shot the same day we shot steel at 910 yards.

    Back tracking on my app, I would need to have a muzzle velocity of 3050 fps to have 5.5 mils at 910 yards so I can either change my velocity in the app or I can change the sight correction factor from 1 to 0.9. Either way I get the same data as seen in the field of 1.8 mils at 455 yards and 5.5 mils at 910 yards. Now I know I'm not getting 3050 fps out of my 7wsm. I can't get enough powder in the case to do that without blowing something up and its certainly not the BC.

    I'll get back out in a week or two and run a tall target/box test on the scope. If the scope is tracking true I'll run some more field data with the sight correction factor in the app and see how everything works.

    BTW, I have used two different chronographs, a shooting chrony and a magnetospeed and both showed roughly the same.
     
  10. doctorjj

    doctorjj Sharpshooter

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    Did you re-verify that your zero was still correct?
     

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