Still can't by my dope ?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Down Under Hunter, Mar 9, 2008.

  1. Down Under Hunter

    Down Under Hunter Well-Known Member

    Messages:
    912
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    May 10, 2007
    The ongoing mystery continues with learning how to use exbal and my new rifle.

    Today I went out and fired a cold bore shot at 1100 M. This was with 32.25 up. Exbal said 34.25 up.

    Conditions were

    89 temp
    RH 42 %

    FPS entered was 2830


    I believe that my other data may be inaccurate as I had an Alt reading that was vastly differerent to the last time I fired from the same spot.

    I have hopefully corrected this by calibrating the kestrel with a ALT and BP reading from the local airport weather station when I got home.

    Anyway as the temp rose and conditions worsten I decided to just fire at a close target of 415 M.

    Entered the range and a BP of 29.66 and dialed the 7 up and sailed at least 2 moa over the top. At this stage I did not think there was much up draft happening as the wind was 10 oclock 3-4mph.

    This shot is down hill 20 degrees for 200 then rises about the same angle to the target.

    I used cosine .99.

    After the forth shot my elevation correction was back to 4 moa up and I still went over the top of the plate. Wind had swung to 7 0clock following and around 6 mph. Then I gave up because I felt either the high temps where at work again or something very fundamental is wrong in my settings To hit the plate I would of had to be less than half the ups exbal gave me ? Over a distance of only 415 this does not seem possible to me ?

    I am going to check the 100 meter zero again, and short of the gun being way high at that range I am lost ?

    Can anyone suggest what else I have not thought of that could cause the PDA and actual ups needed being so different ? I understand that the BC given to the 300 SMK by exbal is very accurate. The way I am going, the PDA is worthless when it is so far out.

    What factors would you need for a 338 edge doing 2830 to only need less that 4 moa up over 415 m. I just dont see weather conditions being that big an influence over that distance ?

    I have given the scope height 2 " above the bore which I think is reasonably accurate.

    Hunting season starts in a few weeks and now I am tearing my hair out !

    If I find this week that the 100 zero is dead on, where do I go ?

    Signed....Frustrated..Cheers DUH
     
  2. Down Under Hunter

    Down Under Hunter Well-Known Member

    Messages:
    912
    Joined:
    May 10, 2007
    I think I have found the gremlin !!!!!

    The NF rail was loose and moving forward and back ! I have removed the scope in its rings and undone the 4 screws holding it down. They were all loose to varying degrees. The rear one of the front 2 had the bottom half of its thread gone and was just spinning in its hole ? I have cleaned the base and screws up and loctited them back in. I will need another screw for the front.

    I feel this will have caused me all my grief. What do you guys think ??

    I feel a bit better now....

    DUH
     

  3. royinidaho

    royinidaho Writers Guild

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    DUH,

    I'm glad you found something. I've been watching your agony/frustration with some intent.

    I sure a glad that gravity still works evenly around the world, even when you are upside down.;)
     
  4. Slopeshunter

    Slopeshunter Well-Known Member

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    Apr 27, 2006
    Good to hear that you've found something DUH. Like Roy said, hasn't been easy reading about your frustrations over the other side of the pond.

    Good Hunting!
     
  5. tjonh2001

    tjonh2001 Well-Known Member

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    Aug 13, 2007
    the real question is did this solve your problem. have you shot it to make sure. i have been in your shoes may times. have a problem then think you have it fixed and realize that it was only part of it. i hope that this does solve it...
     
  6. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Quess I just have to put it back together again after I get a new rail screw from Shawn.

    The movement forward and back surely would cause elevation problems you would think ?

    DUH
     
  7. 400classelk

    400classelk Active Member

    Messages:
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    Oct 19, 2007
    Two words Lock-tite! Hope this helps.
     
  8. Jon A

    Jon A Well-Known Member

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    Two more words: Steel Bed.
     
  9. Down Under Hunter

    Down Under Hunter Well-Known Member

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    May 10, 2007
    Heading to the range in about 4 hours

    Will post the results. I'm sure the rifle will be dead on once again? Heres hoping !!!