Need Help

Discussion in 'Long Range Hunting & Shooting' started by lougonl, Apr 5, 2013.

  1. lougonl

    lougonl Active Member

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    I have 2 long range rifles but will talk about one today. I am having problems with my ballistic solution I cannot get it to match up. I have shot my data and know what MOA is needed to hit zero and several distances but cannot get the balistic programs to match up with this data and I have tried a few programs. I will list the data I have if someone can please tell me what I am doing wrong, I am desperate. I am faily new at this.
    308 WIN
    168 Grain Berger Classic Hunter
    BC G-1 .496 G7 .254
    Muzzle Velocity 2553 FPS
    Sight above bore 2"
    Sighted in at 200 yards
    Elevation 100'
    Temp 65 degree's
    Humidity 65%
    400 5.5 MOA
    500 8.75 MOA
    600 14 MOA
    700 20 MOA
    800 27 MOA
    Please help me!!!
     

  2. yobuck

    yobuck Well-Known Member

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    shoot at some targets at various distances. make note of the (actual) ammount of elevation added in order to hit the target.
    then tweek the velocity numbers in the program to match what you actually got by shooting. thats your chart. not the one gotten by velocity from a chronagraph and a computer program.
     

  3. MTBULLET

    MTBULLET Well-Known Member

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    ballistic programs are only "closeology" , your actual drops need to be verified by shooting YOUR weapon.
     
  4. MMERSS

    MMERSS Well-Known Member

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    Welcome to long range shooting:) Try this, adjust your velocity to match your 800 yard 27 MOA correction and post how far off your program is to matching your 700, 600, 500 and 400 MOAs. For example, after adjusting your velocity to match 27MOA elevation correction post what your computer states for a 700 elevation correction such as 19.75MOA and so on. This may help out with a response. Also post if you are correcting for atmospheric changes from your zero atmosphere conditions to your field conditions.

    Again, welcome to long range shooting.
     
  5. lougonl

    lougonl Active Member

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    Yes you are correct welcome to long range shooting it is making me crazy. I am matching my atmospheric conditions with the conditions I shot the data at.
    I adjusted the velocity to shoot 27 MOA at 800 Yards I will list what happen to the rest of the table.
    400 6.75 MOA
    500 10.75 MOA
    600 15.50 MOA
    700 20.75 MOA
    800 27.00 MOA
     
  6. dragman

    dragman Well-Known Member

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    Remember when that bullet is fired into the chamber it changes the B.C. I almost always find that I have to add FPS to my program before it matches my actual numbers. Once I have a 100 yard zero and a load I am happy with I chrono and build the balistics chart for what the conditions are then take it out and shoot distance. I use the corrected numbers from the real shooting to make the finial chart (and that chart changes with the temp.)
     
  7. MMERSS

    MMERSS Well-Known Member

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    What is your adjusted velocity for 800?

    Also if you could do the same for 700 and adjusted velocity please.
     
  8. BrentM

    BrentM Well-Known Member

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    Are you saying that the info in the beginning of this thread is actual MOA you needed to hit zero at those listed distances?

    What scope and turrent system?
     
  9. lougonl

    lougonl Active Member

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    MMERSS
    My adjusted for velocity for 800 yards is 2495 FPS
    adjusted velocity to hit 20 MOA at 700 yards is 2535 FPS
    Thank you for helping me try to get through this.

    BrentM
    That is MOA that I have shot and hit zero with these #'s of MOA.
    I have a Vortex with 1/2 MOA per click turrent.
     
  10. BrentM

    BrentM Well-Known Member

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    OK. Well I ran your original numbers and I get a result like this:

    400 6.3
    800 25


    To get 27 MOA @ 800 you need 2465 fps. To get 5.5 @ 400 you need 2715 fps.

    On the computer that says your bullet is slowing down/decreasing at an increasing rate that is not normal. Not only is not normal I think it is impossible. I know, bold statement, but physics is usually pretty honest.

    So I am leaning toward 2 things.
    - Scope turrent is not tracking perfectly vertically.
    - shooter eye alignment with scope bore is changing vertically.
     
  11. lougonl

    lougonl Active Member

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    BrentM
    Thanks for your honesty I'm a big boy and I don't take your boldness the wrong way I welcome your honesty. I now have something I can try to correct this problem I have. I will check my trcking on my scope to see if that is the problem, I pay attention to my eye alignment when shooting not to say that is not the problem but will sure try these suggestions. Thanks again.
     
  12. BrentM

    BrentM Well-Known Member

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    I can tell you it takes very little mis-alignment to be off 1 MOA at 400 and 2 MOA at 800.

    I see it more with prone shooting then BR though. Also, I see it with elevated targets relative to the shooting platform. All of those things tend to tilt your forehead forward and down. This changes your alignment a little which pushes the reticle vertically. I bet if you close your eye's and line up behind the scope, open them, note target alignment, then tilt your forehead forward and down a little you will see the shift in reticle to target alignment.

    This may not be happening to you at all, but it does help explain the impact points. BTW- when I shoot my bow at 20 vs 80 my site picture changes a little due to my head positioning. I have mostly corrected this issue but with fixed sights it is not as big a deal. Similar to the bow the rifle has to change position to fling lead long distance. It changes the rifle to shooter position even if it is subtle.
     
  13. lougonl

    lougonl Active Member

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    BrentM
    Rookie mistake on my part but I am having the same issue with my other rifle also but not in as great of a distance apart and I have mounted both of these scopes without a level, I am excited about leveling them and trying again. At least I have a direction I was getting very fustrated and shooting a bunch of bullets which is not a bad thing. Thanks again and I will let you know how thing come out in a couple of weeks.
     
  14. MMERSS

    MMERSS Well-Known Member

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    Ok, great. Can you post the MOA differences using the 700 velocity data for 400, 500, 600 and 800 yards?