Help Needed with LB3.0 and .338 Bergers

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Broz, Jun 6, 2010.

  1. Broz

    Broz Well-Known Member

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    Well if you guys that have LB3.0 figured out are not sick of me or mad at me yet, :). I would like to ask for assistance. I feel, or, I hope, I have enough good solid data gathered to tune the curve in LB 3.0. I will give a summery of what has been done and rifle specs and see what you all think is needed to get my dial ups to match my drops.

    Here we go.

    Rifle is a .338 Lapua mag with 1 in 10 twist 27.5" tube.

    Load is Lapua case, 91.5 gr of H-1000, CCI 250, .015" off the Lands.

    Chrono was 2820 but I have found this chrono to be 30 fps fast when compared to others. So I feel 2790 MV is accurate.

    ES is in single digits with 5 tested.

    Sight in data:
    MV 2790
    BC .455 / G7
    DC .500
    Click setting .250
    Sight Height 2.10
    Zero Range 300 yds
    zero height 0
    incline 0

    Zero was dead on 3 shots touching

    700 yards test
    FC= temp 68*
    Baro=25.8
    Alt= 3920
    Overcast, light head wind 3 mph to 0
    Group average was 2.5" low 10.5 moa up was used

    1042 yard test
    FC= temp 68*
    Baro= 25.8
    Alt= 3920
    5 mph 12:00 head wind, light mirage, .25 moa added for headwind
    Average group was 10" low 21.75 moa up was used

    1342 yard test
    FC= 68*
    Baro= 25.68
    Alt= 4054
    Mirage increasing, overcast to sunny, 11:00 wind at 6 mph
    Group average was 5" low 34.25 moa up was used.




    I just shot these 3 test groups. The Bergers were holding .6 moa at 1342 and .5 moa or less at 1042 and 700.

    I also have the windages used but would like to get the ups dialed in first.

    I do appreciate any and all help. I really need this perfected to extend my effective range for hunting past 1150 yards.

    Thank You!

    Jeff
     
  2. bigngreen

    bigngreen Well-Known Member

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    I've been able to get the numbers real close but I don't like what I have to do to get it.

    I have a couple questions. Have you calibrated your Kestrel Baro/altitude? Have you check that the scope is moving true MOA?

    One thing that would possibly work is to shoot over your chronograph at 4 different ranges and use the DC function in the Analyzer tab. That will give you a BC and drag that is specific to your set up.
     

  3. Broz

    Broz Well-Known Member

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    I agree, you really have to stretch numbers to even get close.

    Yes, durring this process I did re-calibrate my kestrel.

    Yes, twice with 3 shot groups. I have checked the scope at 100 yards for moa / inches. zero , 10, 20, 25, 30, 35 moa. It is spot on to 20 some moa but adds a bit more than it should at 35 moa. But all in all is whith in .5 moa.

    Which as you can see is just backwards to what the actual drops showed.

    I could shoot more at a chrono at distances. But still we should be able to find those majic numbers for BC, DC and MV. By just adjusting it with the drops I shot today.... Correct?

    I should also say. I was very good with the 300 SMK and a banded BC of .768 using exbal. My velocity was very close to what I chronod too. I shot this combo from 700 to 1400 yards regularly. I have also taken a yote at 880, a small deer at 1137 and an elk at 1130 all one shot kills with exbal and 300 SMK's. It was when I started using the new Bergers that I started having trouble. So I purchased LB3.0 and have been struggling since. Don't get me wrong, the Bergers have recorded steller groups. I am confident I can shoot very close to .5 moa to 1400. But just cant get the come up right.

    Jeff
     
    Last edited: Jun 6, 2010
  4. bigngreen

    bigngreen Well-Known Member

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    That's kinda what I figured you would say :rolleyes: hummmmm! The G1 Bc of .891 seems to be closer but still not within the range that we can just tweek the drag.

    We could tweek the numbers to get it right but you don't really know what is the real culprit, using true numbers is the goal. Using the Analyzer BC function of Loadbase basically gives you the BC and drag of that bullet in that rifle.

    Using a G1 BC of .800 and a .500 drag and all other numbers left alone I get seriously close.
     
  5. Broz

    Broz Well-Known Member

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    After playing with the numbers here for quite a while. I have found that using a these numbers get very close. Close enough that I want to retest with them. Unless someone can see me headed in the wrong direction again.

    MV=2780
    G7 BC = .415
    DC= 300

    Wu chu tink? :)

    Jeff

    gun)gun)
     
    Last edited: Jun 7, 2010
  6. bigngreen

    bigngreen Well-Known Member

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    You said you can get accurate drops for the 300gr Sierra from Exbal, have you tried it with LB to see if you can accurately predict the same drops as Exbal with the Sierra. That could shed a little light on the problem.

    You could shoot with your latest numbers but I think I would find a way to at least run the BC test in the Analyzer as you only need two velocities over one range to get a G1-G8 BC. The DC function in the analyzer you have to shoot four ranges but it also gives you the BC and drag. If you do the BC test with a muzzle velocity and a velocity at your 300yrd sight in it may show you that your rifle is producing more drag, the farther you can shoot and get a reading the better the data will be.

    If my back wasn't so tweeked I'd load up the crony and my steel plates and give you a hand!gun)
     
  7. Eaglet

    Eaglet Well-Known Member

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    [​IMG]


    I will try to explain what I did; you got to promise me you won't shoot me! That's for you Jeff! :)




    I asked my self, what are the positive things in this project? The answers came right along.
    • Broz is a great shot with good equipment​
    • I have an awesome Ballistic Program to work with​
    • Bryan Litz G7 BC are mighty trustable and...​
    • I can pray to have the Lord help me.​
    Then I though, what are the things that are bothering me about this project... The answer jumped in front of me... MV!!!!! After looking at all the data and the different results I was convinced that something was very wrong and it had to be the muzzle velocity... no doubt!!!​




    **************************************** ​

    I gave load base the zero info and assumed the the conditions were the same as the first two set-ups at 700 yd and 1042 yards.​


    Note: LB3.0 uses angles for wind directions. 5 minutes is 30° or 2 O'clock is 60° 11 O'Clock is 330°. Personally I like the clocks better. Just keep this in mind.​

    For 700 yards, I used a 0° wind direction (12 O'clock) at 3.0 mph; LB3.0 says to go up 10.3 moa. Broz used 10.5 moa and was 2.5 inches low. So... 0.2 moa higher than what he needed means (0.2*1.047*7) = 1.47" It should have been 1.5 + 2.5 = 4.0" low. In all truthfulness Broz was 4.0" low at 700 yards. Now, 4" at 700 yards means (4/1.047/7) = 0.5 moa. Then 10.3 moa (the original drop) + 0.5 moa (the adjustment) would need a total of 10.8 moa to be right on target at 700 yards.

    Great, I need to start dropping my MV until I get to need 10.8 moa and then compare it to the next two shooting settings and continue wit my adjustments. But before I started dropping the MV, I decided I needed to know what my come ups would have to be for 1042 yard and 1342 yards.​

    Let's do the next one...​

    With the exact same info in LB3.0 I changed the wind speed and direction to 5 mph at 0° again. LB.3.0 said I needed 21.1 moa to be on target. Broz used 21.75 moa; he used 0.65 moa more which means he should have hit 7.1" higher at 1042 yards. (0.65*1.047*10.42) = 7.09"​

    The center of his group was 10" low. Let's add 10 + 7.1 = 17.5" I would need to come up 1.6 moa more and that'd be a total of 22.7 moa at 1042 yards.​

    Now the last one...​

    I turned on the field conditions because the environment conditions changed. I keyed in the new conditions, entered the 330° for wind direction and 6 mph velocity.​

    LB3.0 said that I need 32.5 moa. Broz used 34.25 and was 5" low. Now he used 1.75 moa more than it called for to still be 5" low... So 1.75moa*1.047*13.42 = 24.6" at 1342 yards plus (+) 5" = 29.6" which is 29.6/1.047/13.42 = 2.1 moa. Now 2.1 moa + 32.5 = 34.6 moa for total corrected adjustment.

    ******************************************************'​

    AT this point I need to bring my MV down and play with BC and DC to be able to obtain as close as possible come ups the would look like so:

    700 yards would have to say -10.8 moa

    1042 yards would have to say -22.7 moa

    1342 yards would have to say -34.6 moa

    ARE YOU READY TO BE SHOCKED!!! HERE WE GO!!!!​

    [​IMG]

    When using the muzzle velocity of 2705 fps and without changing the G7 BC's value and setting the DC = 0.492 The following results are obtain:

    [​IMG]
    If we had used the Coriolis effect it would probably be even more adequate.

    Remember to change the wind direction and speed as well as turning on the field conditions for the last group at 1342 yards since the conditions were different.

    Cant wait till you check it and let us know what it does.

    The new muzzle velocity does make sense to me since you're using 91.5 grains of H1000 and you're barrel is 28.5 inches long.

    In all my calculations there was an extra step that I did, I did not have to do it, just because I wanted to make sure that all was being referenced to LB3.0 original drop info.

    Well I do hope this works!!!
     
    Last edited: Jun 7, 2010
  8. Broz

    Broz Well-Known Member

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    Eaglet, all I can say is wow. :)

    I admire your tallent with numbers. :cool:

    Lets reflect a bit of recent history here. Your findigs make me recall the day or two I first spent with the Bergers and load development. My load that I used with the 300 SMK's of 92.5 gr of H-1000 was showing slight pressure with the Bergers. I backed it off 1 gr. as I am not a fan of hot loads. So I needed to find that new MV.

    I had heard that the Bergers were faster due to the less barring surface too. So first thing I did was plug all my info into exbal and then do a "Tragectory Validation" at 700 yards. My proven drops with exbal and the smk's used a MV of 2805, this load chronographed on my chrony either side of 2850. So ater the tragectory validation at 700 with the reduced charge and the bergers it was showing a MV in the low 2700's I don't rember exactly but like 2710 or so.

    I was troubled by this, how could 1 gr drop me 100 fps, people had stated the bergers were faster too. I had a hard time believing this. So I started asking questions and was quickly told my method of dropping MV was a poor practise. I agreed, and bought LB3.0 as I felt I was behind on technology with ballistic programs. I felt that my mv should be around 2770 or so (just my guess) this was before I chronoed. Then my chrono confirmed this. But obviously is wrong.

    Eagle as I was shooting yesterday at 700, 1042 and 1342, and recording drops. I also noted in my data what I felt was needed for corrections to the dial ups to be spot on at each distance. My recording were 700/10.8 , 1042/22.7 and 1342/34.7. So I am excited with your solution to my problem.

    As soon as I get through this cup of coffee, I will plug this info into LB and Exbal and see how it all works out. Then as soon as I can I will be out shooting again using LB to see how it all applies to real world shooting.

    I also am in search to find a Oehler to shoot my rifle through. I just need to see this.

    Right now I am back to my old belief that most all of us are being fooled by chronographs. I dont think we can spend $100, $200 or even $500 on a piece of equipment, to measure the speed of a projectile 1 1/2" long and traveling at a speed of 3000 fps. and expect this equpment to be accurate. How can something that cost only a few hundred dollars do this? Yet we undoubtingly rely on them. And even more so, we believe that when they say 5 or 10 measured projctiles fell into with in less than 10 FPS of each other, we believe it and are happy. I am not sure I buy this. Right now I think Eaglets method of finding MV is far more accurate than any chrono I have been around in my 40 years of shooting. I also believe that your 1000 yards group is the best test for ES.

    Thank You Eaglet and Bigngreen for your help here. I will send some more lead and report.

    Thanks!

    Jeff
     
    Last edited: Jun 7, 2010
  9. Broz

    Broz Well-Known Member

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    Eaglet, in review I want to clarify. The chart, "impact to be" This is in inches correct?

    And my barrel is only 27.5" long I hope I didnt state that wrong earlier.

    Thanks again!

    Jeff
     
  10. Eaglet

    Eaglet Well-Known Member

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    [​IMG]

    Yes, it's in inches... sorry friend! and you stated your barrel length right, latter I remembered I messed up.

    I enjoyed reading your last post. I'm really hoping this is going to work for you great. When you use a DC (Drag Coefficient) greater than 10, it places a lot of doubt on the bullet's BC; as you can see we're looking good there.

    CORRECTION: "The greater than 10 above is wrong" it should say: a DC change Greater than ±10% of 0.500

    Enjoy!!!
     
    Last edited: Jun 8, 2010
  11. jmden

    jmden Well-Known Member

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    Great conversation, guys. Hard to believe that MV would drop so much, but you gotta make the drops match up and if that's part of the solution in the software...

    Broz, have you tried taking a black felt tip pen and coloring the entire bullet with it? I'm sure you've considered this as you have much more experience than I, but it does seem to give better constency when I have tried it. Just a thought from the suggestions from my chrono's direction sheet.

    Shooting in cloudy weather over the chrono, etc.? Ultimately, though, like you I find a load that works (Jerry Teo's method in article section has worked well and quickly) , chrono it it get a basic idea of MV and make sure it has good grouping at distance and then use Exbal's Traj. Validation to arrive at an MV that matches the drops closely.

    I need to look into LB. Just not sure I have the time right now to learn another program. I've got two other fairly complicatied programs (for me anyway) I'm trying to learn already...:rolleyes:

    Keep us posted,

    jon
     
  12. bigngreen

    bigngreen Well-Known Member

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    Very nice Eaglet!!! I was over thinking it and not wanting to touch the MV. I hate changing the BC, especially one that has Litz involved. And having to change the drag more than a little also bugs me cause it points to a potential data point some where earlier in the process.
    In my 270 WSM I loose 41 FPS with the Berger over the Accubond with the same load. I feel the reason is the bearing length of the bullet allows the bullet to move easier down the bore lowering the pressure in the barrel which in turn lowers the MV.
    Eaglet mentioned Coriolis, I would get a bearing and use it, I was playing with it as a part of the solution and you will see coming into play.

    I learn more about using Loadbase 3.0 every time Eaglet posts, thanks for being patient with us who are still on the low side of the learning curve!!:D
     
  13. Broz

    Broz Well-Known Member

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    I just loaded the perimeters into Loadbase and I now get the same come ups as you do Eaglet. I believe them to be on track and will be shooting again very soon to document this and test new distances.

    Interestingly enough, I loaded the same 2705 mv into my Nightforce exbal program using the G1 BC of .891 and it is spot on too at these ranges of 700, 1042 and 1342 yards.

    I am focused to make my self use LB so I can build confidence and smoothness with my operation of it. If nothing else, I do feel the spin drift, corialis and wind part of he LB program has something to offer. However I find inputting the wind to be confusing using the number of degrees instead of simply using the clock method. Not to mention if you are at 330* (11:00) and want to return to zero you have to go back all the way arond counter clockwise. Would be nice if it would just cross 360* to 0* again.

    I am learning!

    Thanks again!

    Jeff
     
    Last edited: Jun 7, 2010
  14. Broz

    Broz Well-Known Member

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    Jon, good suggestion. I have never tried it. I shot 5 of this load across my chrono and 3 were 2820 and the other two were 2819. I trusted it, silly me:rolleyes::D.

    I want to shoot across an oehler now. If it shows my velocity to be at the 2705 area I wll buy one. If not, I dont feel I need a chrono because I have always had to change the given velocity anyway to match the Balistic programs. Who knows, maybe they are all wrong...lightbulb:D:D

    Jeff