#####Ballistics HELP (PLEASE)######

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by bigbuck, Nov 17, 2012.

  1. bigbuck

    bigbuck Well-Known Member

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    If it wasent for some of you guys like Broz , Shawn and others I would throw my NF ballistics software in the garbage but I have seen photos and video of you makeing extremely long shots so I know it is me but I dont have a clue as to what to do. .... As you can tell im a little frustrated.:) I need help . I cannot get my program to give me the correct elevation dope .

    Example : The last time I shot was at 556 yards ( not that far) so I thought I would atleast be within the 8" circle that I was shooting at .
    I shot a 3 shot group it measured 5" from center to center , I then measured from the center of the group to the center of the bulls eye and it measured 8" high. I can handle being left or right because that could be my wind reading skills but my confidence is lacking on the elevation dope that my program is giving me .

    A question or two and then I will give you all of the details concerning what I had entered into my program the day that I shot.

    1. How close can you get to center of the target with your program at this distance ? What should I exspect or what is the norm ?
    2. Just throwing this one out there , I have never calibrated my Kestrel 2500 NV . Is it possible that its not giving me precise info to input ?

    Now the details of my load and the conditions for the day of the shoot.

    210 Berger
    Rem Brass
    Fed 215M primer
    85.5 Grains of Retumbo
    300 RUM

    Elevation 693
    Temp79.0
    R.H 62.0
    Baro 29.18

    Yardage 556
    MV 2900

    NF called for 8.50 MOA up.

    Note with my program it has a box with a check in it, to calculate the standard pressure and I clear it out . Im pretty sure this the correct way.

    Almost forgot that this is a new pound of powder with different lot number.

    Let me know your thoughts I will greatly appreciate any help .

    I dont have a cosine indicator yet and I was on the top of a ridge shooting down hill. Would this have made me hit high ?
     
  2. Scot E

    Scot E Well-Known Member

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    What is your zero range?

    Atmoshpheric conditions will havealmost no impact on POI inside 5-600 yards so something else is likely wrong.

    I don't have and NF (exbal) experience but can run some numbers for you on Shooter.

    As a reminder there is a free ballistic program here at LRH and it is a good one. Look at the top in the brown heading bar under G7 ballistic calculator.

    Scot E.
     

  3. OneShot0351

    OneShot0351 Well-Known Member

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    Shooting down hill will make you hit high, hastily running your ballistics on the G7 coefficient @ 550 yds 20 degree angle about a minute off, 30 degrees= an tad over 2 minutes off.
     
  4. .284

    .284 Well-Known Member

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    Shooting up or down will make you hit high. If you can figure out the angle you should be able to find a online program to tell you how much. 8 inches at almost 600 yards seems plausible to me though
     
  5. bigbuck

    bigbuck Well-Known Member

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    My zero is at 200 yards.

    I used a B.C of .631

    Thanks guys for trying to help.
     
  6. Broz

    Broz Well-Known Member

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    First recheck zero. I recommend you go to a 100 yard zero. Then change the program to 100 yard zero. Reason is if your groups are 1 moa it will leave more room for error at 200 than 100. Then shoot groups at 500, 700, and 900. Record the field conditions. Then record what you dialed for each group and also how low or high the group center was from point of aim. If a group is abnormally large shoot it again. Once you have this data you can figure what you actually needed to be spot on for center group. Example: The center of group at 700 yards was 3 1/2 " low of point of aim. You used 18 MOA for a dial up. 3 1/2" at 700 is 1/2 moa. So you needed to dial 18.5 moa. Record now what the spot on dial ups should be for each distance with those field conditions. Then using G1 BC of .631 change muzzle velocity in exbal until all match within .25 moa. If you can not get them all on, go for making the farthest ones perfect. If you can't get them spot on remember the accuracy error of your combination. (shooting skill, ammo quality and rifle accuracy)

    A 5" group at 556 yards is almost 1 moa. That is not great so it might be hard to get all 3 perfect. Once you get it close then with your newly calibrated program shoot some more at differences and fine tune if needed. Remember!! It is better to be 1/2 moa off at 500 yards than 900. Because 1/2 MOA at 500 is a 2 1/2 " miss at 1000 1/2 moa is a 5" miss.

    PS: I have used that .631 BC for many .308 cal rifles with 210 VLD's. It has always worked well out to 1200 yards.

    My rifles shoot spot on to center of group within the combinations accuracy. That is 1/2 MOA to 1500 on an average.

    Yes a slope will make you go high. But it would have to be a pretty steep slope at 556 for 8".

    There is a reason I buy powder in the same lot and 40 lbs at a time.



    Jeff
     
    Last edited: Nov 17, 2012
  7. kcebcj

    kcebcj Well-Known Member

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    I just ran your dope in Exbal and got the same results. Then I punched in a 25 degree slope and there was about a 8 inch difference. So I would guess that the slope you speak of is the culprit. 25 degrees is not a lot of slope. Your velocity may have changed a little either way with the new can of powder?? I'm assuming you have verified the drops beyond the 550 right?


    That's all I got....sorry.
     
  8. bigbuck

    bigbuck Well-Known Member

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    Thanks Jeff.
    Do you zero your rifles at 100 yards ? Or are you saying I need to in order to get more accurate dial ups ? Would it be okay to adjust my MV and leave my program the same, say instead of a 2900 MV setting I could try 2915 and see how my impacts looked ?

    kcebcj I havent varified drops with this powder past 556 yet. I would think the error would just graduate . IMHO
     
  9. shortpants

    shortpants Well-Known Member

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    It took me a long time to learn to get a calculator to match my drops but I've finally done it. First piece of advice is only test on great condition days. If conditions are questionable then your results will be too. It is absolutely crucial that you are 100% confident in your zero wether it be 100, 200 or whatever. If you are testing drops always start with verifying your zero. Beyond 400 yards angle becomes an issue. In my experience I don't see a lot of shots beyond 400 that are more than 25*. When I have seen angles like that it is a very steep canyon or mountain side. Most people over exaggerate angles. If you are indeed testing at extreme or even moderate angles you need to find some way to try and figure in the angle. A guess might be better than no consideration but I advise you find a way to measure the angle. Like Jeff said shoot at various yardages (400,600,800,1000) for example. Does not have to be exact as long as distances are known to be accurate. An error in range can make you scratch your head. Shoot good groups! Adjust velocity until your calculator matches your real world drops within .25moa. It may take several trips before you settle on the perfect velocity but by keeping track of conditions, verifying zero every time, and knowing the angle you should be able to establish a solid baseline. Then stop shooting groups and go hunt some rocks!!! I just re-watched one of Shawn's videos again the other day and that's what stuck with me the most. Once your done testing stop shooting groups. You'll drive yourself mad! I'd like to thank Shawn and Jeff as well as Michael Eichael. These 3 guys have finally got this stubborn SOB on target. It's a good feeling when you can trust your calculator! Good luck my friend and keep us posted on your progress.
     
  10. shortpants

    shortpants Well-Known Member

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    Just FYI I had to cut my MV 80fps from what my chrony is reading to match my real world drops. Don't be afraid to adjust the velocity.
     
  11. bigbuck

    bigbuck Well-Known Member

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    Thanks for the reply/advice.

    I know now why Jeff is saying he buys 40 pounds of powder . Next time I am going to buy several pounds of the same lot.

    One question if my MV is set at 2900 FPS and I hit high (while shooting on flat ground ) which direction should I adjust add 10 or 15 seconds or take away ? since I am shooting high . Thanks
     
  12. shortpants

    shortpants Well-Known Member

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    Remember before you make any changes you must verify your zero!!! Then on level ground if your high that means your bullet is going faster so you should add whatever amount it takes to get your come up on your program to raise up 8".
     
  13. bigbuck

    bigbuck Well-Known Member

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    I have verified zero it is dead on at 200 yards I shoot at the little stickers that come with the 6'' sticker . They are the size of a penny and I can put one shot in the small sticker 2 out of three. elevation good and windage good at 200 yards.

    If my bullet is going faster wouldnt that mean that I should add whatever amount and it would in return call for less dope therfore lowering my impacts or am I thinking about it wrong ? Thanks
     
  14. Broz

    Broz Well-Known Member

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    I have been all the way out to 300 with zero's. I am now back to 100 for these reasons. Ease to find a place to check zero. Wind and mirage screw with it less. And smaller groups to center up.

    If you want to leave it at 200 that's fine. But before you do any adjusting check the zero. If your zero is off 1 moa all your dial ups will be too.

    Quote" One question if my MV is set at 2900 FPS and I hit high (while shooting on flat ground ) which direction should I adjust add 10 or 15 seconds or take away ? since I am shooting high "Unquote

    If you are hitting high it is because your program has a velocity that is too low. As you raise the velocity in the program it will tell you to dial less moa.

    Jeff