dont know what to do

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by doublebull, Mar 20, 2011.

  1. doublebull

    doublebull Member

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    I went shooting today to practice for my first 1000 yard shoot I shoot a 6.5 284 that i built its got a 28 inch barrel with the ratchet 4 riflings in it i shoot 140 gr berger and have a ballistics program on my i pod i shot at 220 yards without making adjustments it was 2.5 inches low then i shot it out at 420 yards and was 21 inches low then went to 600 and i had to dial up 9 moas i put that in my program and it said i had a bc of 1.75 i shoot 2970 fps just was wondering if someone had any ideas. im lost i was also shooting at 3270 feet elev. every thing matches for that bc
     
  2. retiredcpo

    retiredcpo Well-Known Member

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    Are you sure about your FPS Did you chrono the loads at around the same temp/alt?
     

  3. doublebull

    doublebull Member

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    ya i ckecked it through two diff cornys
     
  4. trebark

    trebark Well-Known Member

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    Your ballistic program should have a basic set of information to input, then it will give you a drop chart that should be relatively close to reality.

    If you can provide some more details, I am glad to run the numbers in Exbal and post the drop chart that it produces. Here's what we have and need....

    Bullet: 140grain Berger VLD (or is it the Long Range hollow-point boattail?)
    BC: .612 for the VLD (the LRHPB is .618)
    Muzzle Velocity: 2970
    Elevation: 3270
    Site-in Temperature: ??
    Scope Height (distance from center of bore to center of scope): ??
    Site-in Distance: 100yards?
     
  5. doublebull

    doublebull Member

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    it is 1.5 in scope hight 50 deg its the vld i ran the bc .612 and it said 10.9 moa but the moa i used to be on target was 9 moa and i produced a 3 inch group at 600
     
  6. rscott5028

    rscott5028 Well-Known Member

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    You were 2.5 low at 220. So, I re-ran your numbers with a 220yd zero using NF Bal.

    @ 420yds, it shows you would have a 19" drop. Then, you would add another 2.5" because you weren't exactly zeroed at 220. Hence, you should've been 19+2.5=21.5" which is close to the 21" you stated.

    @ 600yds, it shows you would have a 56.5" drop or ~9 MOA elev adj. Then, you would add another 2.5" because you weren't exactly zeroed at 220. Hence, you should've been 56.5+2.5=58" which is still close to the 9 MOA you stated.

    @ 1000yds, it shows you will have a 231.1" drop or ~22 MOA elev adj. That should leave you about 2.5 low.

    That's not the most scientific method. But, it should get you on paper or steel.

    How many rounds have you chronied and how consistent is your MV?
    That will be a big factor.

    Good luck!
    Richard
     
  7. retiredcpo

    retiredcpo Well-Known Member

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    I entered your info into my program and got
    36 clicks to get to 600 yards or 9MOA

    700=48 clicks(12 MOA)
    750=54 clicks(13.5 MOA)
    800=60 clicks(15MOA)
    850=67 clicks(16.73 MOA)
    900=74 clicks(18.5 MOA)
    950=81 clicks(20.25MOA)
    1000=88 clicks(22 MOA)
     
  8. doublebull

    doublebull Member

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    my program you put in your zero range then the target range and then you put in how many inches low you are and when i did that it said it was a to high of a bc so i did it manually untill all three ranges that i shot were the same i dont know i have to work all week then on fri we sight are guns in just would like to know so i dont look dumb dont know what bc to go with
     
  9. trebark

    trebark Well-Known Member

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    Dropped all your data into Exbal and here is the resulting table.

    [​IMG]



    It would not be surprising that your actual adjustments might differ slightly. Exbal has a trajectory validation function where you can input the variances and it will automatically adjust. You might want to see if your program has such a function.
     
  10. rscott5028

    rscott5028 Well-Known Member

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    doublebull,

    I like to establish a good/known zero and set my turrets to match.

    From the info you provided, it looks like your zero is around 155yds.

    But, perhaps I didn't understand all the info you provided.

    Trebark's table shows you -4.3" at 225 yds. But, you seriously outperformed that with -2.5". So, you do not have a 100 or 200yd zero. Or, you changed your shooting position or technique between sessions.

    If you can establish a solid 100yd zero, or zero your turrets with your POI 4.3" low at 225yds, his table will be very close.

    In any case, I seriously doubt that the published BC for the Berger 140 is incorrect. They take that stuff very seriously.

    It's far more likely that some other input is off a bit.

    -- richard
     
  11. backwoods83

    backwoods83 Well-Known Member

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    I shoot 6.5x284 in 1000yrd ibs you will need 24.5-26moa depending on conditions, I use 139 lapuas at 3020 .617bc @1750ft and I usually settle around 25 3/8 moa. Good luck!
     
  12. doublebull

    doublebull Member

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    well i went out and shot my gun at 1000 for sight in and it was 19 moa i still dont know whats going on but i shot good
     
  13. backwoods83

    backwoods83 Well-Known Member

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    You must be shooting in some thin air, like 6000ft DA that's pretty impressive.
     
  14. doublebull

    doublebull Member

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    well it was raining to day so would that be thick air? I dont know im stunned about it and i shot a hundred yards to make sure it was zeroed