Couple ballistics calc questions...

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by hh4whiskey, Dec 29, 2013.

  1. hh4whiskey

    hh4whiskey Member

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    Don't get to my PC sometimes, and generally use a few ballistics apps in my phone...mostly let fly dlxz. Seems to be pretty good for most of my needs, but I'm using the G7 BC option for studying some 7mm LRABs in 150 & 168, and the #s it's giving me are pretty hard to believe. Using the G1 BC, I know isn't accurate for that profile either, but they should be relatively close (I'd think), and they're WAY different....300+FPS off at 500. My other apps don't have a G7 option. So, anyone got #s or anyway to compare what I have or another recommended app that allows G7 BC input?

    Thanks.


    700'/55deg
    150 .284 LRAB = .611/G1&.309/G7&1.380"L

    150@2850mv

    YD DROP FPS FTLB
    50 0.119 2809 2628
    100 0.623 2770 2555
    150 0.004 2730 2482
    200 -1.796 2691 2411
    250 -4.811 2652 2342
    300 -8.971 2614 2275
    350 -14.499 2575 2208
    400 -21.354 2537 2143
    500 -38.982 2462 2019

    168 LRAB .652/G1&.353/G7&1.490"L
    168@2700

    YD. DROP FPS FTLB
    50 0.241 2665 2649
    100 0.746 2632 2584
    150 0.005 2598 2517
    200 -2.040 2564 2452
    250 -5.424 2531 2389
    300 -10.063 2498 2327
    350 -16.200 2466 2268
    400 -23.785 2433 2208
    500 -43.209 2369 2093
     
  2. Michael Eichele

    Michael Eichele Well-Known Member

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    You have to adjust the actual BC number when you switch from g1 to g7 or vice versa. Some apps do it automatically and some don't.
     
  3. hh4whiskey

    hh4whiskey Member

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    Yep, was doing that, as well....the #s just look too good/different. Let Fly requires manual BC input, when using a non-catalogued bullet.
     
  4. varmintH8R

    varmintH8R Well-Known Member

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    I ran the 168's in Bulletflight using your parameters and a 150 yd zero.


    Using the G7 at 500 yds I got: -47.9 in , 2118fps, 1673 fpe

    Using the G1 at 500yds I got: -48.9 in, 2072fps, 1602 fpe

    Pretty close using that software (except the energy doesn't make sense to me). Much lower velocity than what you got. I'll run it on JBM for giggles too.
     
  5. varmintH8R

    varmintH8R Well-Known Member

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    OK,

    Using JBM, same parameters:

    Using the G7 at 500 yds: -48.3", 2100fps, 1645 fpe

    Using the G1 at 500 yds: -49.3", 2058fps, 1579 fpe

    Pretty close to Bulletflight. You may have a glitch in your ap?
     
  6. valleyloader

    valleyloader Well-Known Member

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    I remember reading on another thread about the 210 accubond where they found the actual G1 BC to be the same as the 210 berger VLD G1 BC of .631 not the advertised .730. If you have confirmed your velocity try adjusting the BC in the software until it lines up with your hits, you will likely find that the BC of these bullets are overrated. Not sure where nosler got their data but the first thing I thought about the 210 gr. was that it was too good to be true and it likely is.
     
  7. hh4whiskey

    hh4whiskey Member

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    Your G1#s line up with mine. That shows me the difference. Thanks.

    FWIW, I'm just scoping #s for high BC hunting bullets, pushed to 7x57 handloading velocities. Sorry, but for my uses, Bergers would never be a consideration. Barnes probably won't, either. Old school cup and core, for now.