Elevation Correction Issues

Discussion in 'Long Range Hunting & Shooting' started by Blacktail, Jul 7, 2018.

  1. Blacktail

    Blacktail Well-Known Member

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    Finally got a chance to shoot 500 and 1000 today. I used the gunwexrks ballistic calculators and at 1000 it was way off. For example my 7/08AI pushing a 120 ttsx at 3150 called for 20 MOA adjustment after a few rounds finally saw vapor trail hit low went to 29 MOA and scored hit. That baffles me. There was a 15 mph head wind. I am not sure if maybe my muzzle velocity was off or maybe just me but 10 Moa off seemed odd to me. New to shooting this far everything has been 500 and in prior but also noted at 500 it was a MOA off meaning called for 5 MOA and used 6. Thanks for the help
     
  2. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Atmospheric inputs, zero, vel, bc, scope click values, and every rifle seems to have a different effect on the bc. Your solution is off a lot. Could be a bit of everything? At 1000y the retained vel is getting very low with this combo and it may just be beyond its ballistic ability.

    Steve
     
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  3. Barrelnut

    Barrelnut Well-Known Member

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    I think you have some information entered incorrectly in the ballistic calculator. I just ran the 3150 FPS with a 120 TTSX with G1 BC 373 and a 15 MPH headwind and got 28.2 MOA for 1000 yards. I used the Shooter app on my Android. That is much closer to the 29 MOA you were successful with.
     
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  4. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    I was just about to say that, I'm not sure what the zero is but 20moa sounds really low of the top of my head.

    Steve
     
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  5. Barrelnut

    Barrelnut Well-Known Member

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    Yes, I agree. 20 MOA is 300 RUM territory. I just ran the numbers above with a 100 yard zero and 4200 feet elevation.
     
  6. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Yep 3400fps with a .6+bc bullet.

    Steve
     
  7. The Oregonian

    The Oregonian Well-Known Member

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    Yep
    Yep. My 28N witht generic atmospheric come out around 21 MOA with the 195’s.
     
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  8. codyadams

    codyadams Well-Known Member

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    At 1000, 20 MOA is about what my .260 AI uses sending 147 eld-m's at 3040 fps (20.25 moa to be exact), at 6600 ft elevation. No way a 7mm-08 is doing that with the low bc 120 grain barnes, in any practical atmospheric condition.

    Check and double check your inputs, something is off . You possibly entered the G1 bc as a G7 bc.
     
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  9. HARPERC

    HARPERC Well-Known Member

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    Others have plugged in ballistic solutions closer to what you're seeing so that should have you closer to the mark.

    Most of our equipment comes with +/- tolerances, and when they offset each other life is great. When they don't it's tough sledding, and isolating one thing can be difficult.

    Unless you measure, and monitor every thing, you're guessing, and the farther you shoot the bigger the error.

    I saw David Tubb talking ELR, he was using a chronograph for every shot to ensure he didn't chase a zero based on a round that just was on the low side velocity wise.
     
  10. Andrew Massi

    Andrew Massi Active Member

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    Unless that ttsx is doing 3550 ;-)
     
  11. Blacktail

    Blacktail Well-Known Member

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    I just did same thing and came up with 30 moa. The big issue was my 7 mm STW it was way off too so changed things and Ted when I clicked on the drop chart things weren’t changing maybe a comparability issue with my Mac and the gunwerks site not sure but thanks for all the input guys. Which app are most of u running on iPhones?
     
  12. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Ballistic ae

    Steve
     
  13. The Oregonian

    The Oregonian Well-Known Member

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    I run shooter...but in the field I use a G7.
     
  14. codyadams

    codyadams Well-Known Member

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    You do that with a 7mm-08, let me know so I can be at least a county away....lol.
     
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