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Loadbase 3.0 and Exbal

 
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  #36  
Old 09-14-2010, 09:00 AM
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Join Date: Aug 2008
Location: Arvada, Colorado
Posts: 367
Re: Loadbase 3.0 and Exbal

bigngreen,

Nice shooting and thanks for the info. I agree with Broz, if you play around with your trajectory validation you should be able to get everything lined up.

I did a little shooting myself yesterday. Here's my results:

9/12/10
10:30am-2pm
wind 2-7mph from 270 degrees.
temp 89
Azmuth 0
latitude 39.5
300 yard zero
baro 25.21
Humidity 11.8
lots of mirage, dancing a little.

Load
100gn Retumbo
Fed 215 mag primers
.020 off lands
2933 fps

800 yard target
Lb called for 12.4 moa Up and 1.5 moa left with a 3mph wind. I dialed 12.5 up and 1.5 left into my Nf. Here are the results. he 3 white circles are my 800 yard group. I covered them with white circle because i was lazy and did not want to put up another target .

1000 yard target
Lb called for 18.5 moa up and 1.75 moa left with a 2mph wind. i dialed 18.5 moa up and 1.75 moa left. The 3 shots that are not covered up are my 1000 yards shots. The hole on the X is not a bullet hole, it is a marker I use to hold a 2" orange disk I shoot at.



I messed around with LB and if I use 2975 fps as my velocity my dialups are spot on at all distances shot yesterday. I shot 300, 500, 800 & 1000 yards. Need to get out this week to test one more time before my Bear hunt this weekend.

One thing I did like was having Spin Drift and Coriolis turned on. If I would have left them off I would have been another 10 inches to the right at 1000 yards.
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  #37  
Old 09-14-2010, 09:21 AM
Gold Member
 
Join Date: Jul 2006
Location: AB, Canada
Posts: 555
Re: Loadbase 3.0 and Exbal

Hi to all

What I noticed with my exbal settings are the following.
1. setup your Sight In Condition (and use real value of the bullet speed form chrony)
2. Input values for Bullet Data/Field Cond/Target Engagement
3. Take shoots at 100 - 500-700-900-100-1400-1700yrds
4. Play with MULTI BALLISTIC COEF TO MATCH YOUR FIELD DROPS

If you are using the Trajectory validation to match your drops beyound 1200yrd, without playng with Ballistic coef, will get you off inside 900yrds.

If you noticed you are off at 1000yrds, just see the Velocity Value for 1000yrds, and then go and modified on Balistic coef field the Bullet BC for that speed.
Then repeat the above for 1400yrd.

Using Multi balistic coef to tuneup your field drops, It gets me with 1-2inch close with JBM balistic predictions using G7 - up to 1900yrds for my 338edge with 300smk.

I push 300SMK at 2848fps
The Balistic coef value are:
0.795 - 3150
0.780 - 2600
0.770 - 2400
0.750 - 0

bullet data 2848 - sight in 100yrds, 42F, 50% humid, 24.69in/Hg.


If someone is doing simmilar, please chime in...
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Thanks
CJ
My 338Edge

Last edited by 300rum; 09-14-2010 at 09:24 AM.
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  #38  
Old 09-14-2010, 09:30 AM
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Join Date: Nov 2008
Location: SW Montana
Posts: 4,437
Re: Loadbase 3.0 and Exbal

I ended up sighting in a little weird with 5.5 high at 200, I was screwing around with the programs one day and shot a group at 200 with almost unmeasurable vertical and a group at 590 that had a 1/2in of vertical so I decided that the data was so tight that I would leave it as is instead of getting a true 200yrd zero, which I have a real hard time doing, for some weird reason

What is interesting about what I shot last night is that I used Exbal to give Loadbase numbers, both programs using G1 and the same numbers everywhere, Loadbase, I'm not using Spin or Coriolis with either because it is the easiest way to run them on equal footing. Loadbase is constantly higher once you get out there past a 1000yrds. 1450 is absolutely maxing my 270 WSM out because of the speed lose due to worn barrel, I'm just inside transonic at 1450 so I think, at least till the 338 Norma is born or I get the barrel screwed on my 270 that's max!
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  #39  
Old 09-14-2010, 09:39 AM
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Join Date: Jul 2006
Location: AB, Canada
Posts: 555
Re: Loadbase 3.0 and Exbal

Quote:
Originally Posted by bigngreen View Post
I ended up sighting in a little weird with 5.5 high at 200, I was screwing around with the programs one day and shot a group at 200 with almost unmeasurable vertical and a group at 590 that had a 1/2in of vertical so I decided that the data was so tight that I would leave it as is instead of getting a true 200yrd zero, which I have a real hard time doing, for some weird reason

What is interesting about what I shot last night is that I used Exbal to give Loadbase numbers, both programs using G1 and the same numbers everywhere, Loadbase, I'm not using Spin or Coriolis with either because it is the easiest way to run them on equal footing. Loadbase is constantly higher once you get out there past a 1000yrds. 1450 is absolutely maxing my 270 WSM out because of the speed lose due to worn barrel, I'm just inside transonic at 1450 so I think, at least till the 338 Norma is born or I get the barrel screwed on my 270 that's max!
The reason why you are out past 1000yrds, is because your BC is to high for the speed past 1000yrds.
Unfortunately the Exbal is using bc and speed to match your drop.

So just go and imput multiple BC values past 1000yrd and you will be fine.
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My 338Edge
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  #40  
Old 09-14-2010, 01:16 PM
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Join Date: Apr 2005
Location: Alaska
Posts: 3,365
Re: Loadbase 3.0 and Exbal

Quote:
Originally Posted by SHRTSHTR View Post
One thing I did like was having Spin Drift and Coriolis turned on. If I would have left them off I would have been another 10 inches to the right at 1000 yards.
Nice shooting, particularly with mirage squiggling the target all around. Hard to hit a dancing bullseye...

Thats what I see for combined spin drift and Coriolis at 1000 yds. 1000 yds is the farthest I've shot. But my 300 Win Mag, 7mm Rem Mag, and 280 RCBS Imp. all show in the neighborhood of ~ 8-12" combined spin + Coriolis drift by 1000 yds.

Interesting and educational thread guys. Thanks for sharing your findings and techniques. There's more than one way to skin a cat, but most people find their favorite method(s). And there's nothing wrong with that. With as much shooting as you guys are doing, whichever method you end up using has been thoroughly field-proofed - resulting in a technique that's just about 'bullet-proof'.

Nice that you have easy access to long range shooting. I have exactly one spot. And the range there is limited to ~1400 yds.
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  #41  
Old 09-14-2010, 02:53 PM
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Join Date: Aug 2008
Location: Arvada, Colorado
Posts: 367
Re: Loadbase 3.0 and Exbal

Phorwath,

Thanks for the kind words. I was happy with my vertical dispersion and both my 800-1000 yard groups were under 1/2 moa center to center.

I am a little confused as to why I am shooting 5 inches high. My muzzle velocity is 2933 fps and I am using a G7 of .381 for my 300gn smk's. Changed my velocitity up to 2975fps and all my drops worked out perfectly for 500, 800 & 1000 yards.

I do not believe I am doing this right. It is hard to believe that my Oehler is off over 40 fps. I think my velocities are correct and maybe I need to try changing my drag coefficient or BC?

Would like to hear what LB users have to say. I could also just reset my NF turret 1/2 moa low at 300 yards and my dialups would be good to 1k. I plan on shooting further sometime this week.
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  #42  
Old 09-14-2010, 03:35 PM
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Join Date: Apr 2005
Location: Alaska
Posts: 3,365
Re: Loadbase 3.0 and Exbal

Quote:
Originally Posted by SHRTSHTR View Post
I am a little confused as to why I am shooting 5 inches high. My muzzle velocity is 2933 fps and I am using a G7 of .381 for my 300gn smk's. Changed my velocity up to 2975fps and all my drops worked out perfectly for 500, 800 & 1000 yards.

I do not believe I am doing this right. It is hard to believe that my Oehler is off over 40 fps. I think my velocities are correct and maybe I need to try changing my drag coefficient or BC?
The best way I know of to sort this out is to shoot over the chronograph at long distance and confirm that the down range velocity matches the LB3 predicted downrange velocity. If it does, then the BC & DC are likely good as is. If not, then tweak the BC or DC so that the predicted downrange velocity matches the measured downrange velocity.

I would add that it could be possible that your chronograph is reading slow at both distances, and you could still obtain a good measured velocity match to the predicted velocity with the correct BC/DC, yet be off on target vertically. This is one reason I decided to build a setup so I can shoot over three separate chronographs concurrently. If they're all in agreement, I have to believe my measured velocity is very close to the true bullet velocity. But I rather doubt your Oehler is giving you incorrect velocity with a 42 fps magnitude of error.

I've never measured the downrange velocity of a SMK yet, but I suspect Bryan Litz's measured G7 BC value is a good one. The equipment he's using has demonstrated itself accurate to within +/- 1%, if I recall correctly. And I have a strong suspicion he's very meticulous with his data measurement and analysis.

Lastly, you're still learning LB3, and as you suggested - there could be some operator issues associated with the learning curve. I have no doubt you'll get it sorted out.

Last edited by phorwath; 09-14-2010 at 04:07 PM.
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