How to adjust b.c. to get ballistic chart to match drops

Lrreloader

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Joined
Jun 18, 2019
Messages
897
Location
Pa
I am using bergers ballistic program on their website, I shot at 300,600,1000 yards results were:
300 called for 3.93 moa. Actual 3.5
600 called for 12.46. Actual 12.0
1,000 called for 27.71. Actual 30.0

Specs: 33 nosler
M.V. 2,780 fps
263 grain hammer hunter
B.C. .325 G7 (from website)
Elevation 1,400 ft
Temp. 59*
No other factors added in.

What I'm looking to do is get chart to mirror real moa from drops @ 1,400 ft so I can adjust elevation to 9,500 ft for Colorado Hunting trip.

Do I just adjust the B.C value until it reads what I got from drops?

Thanks
 

Sako28

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Joined
Dec 22, 2020
Messages
62
Location
ND
Your POI is being changed. It doesn't matter how you do it. Now, in this example, maybe at 1100 or 1200 yards it will make difference what you adjust. But within the parameters of what you verify it doesn't matter.
 

squeeeeze

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Joined
May 21, 2011
Messages
486
Location
Southern Arizona
I am using bergers ballistic program on their website, I shot at 300,600,1000 yards results were:
300 called for 3.93 moa. Actual 3.5
600 called for 12.46. Actual 12.0
1,000 called for 27.71. Actual 30.0

Specs: 33 nosler
M.V. 2,780 fps
263 grain hammer hunter
B.C. .325 G7 (from website)
Elevation 1,400 ft
Temp. 59*
No other factors added in.

What I'm looking to do is get chart to mirror real moa from drops @ 1,400 ft so I can adjust elevation to 9,500 ft for Colorado Hunting trip.

Do I just adjust the B.C value until it reads what I got from drops?

Thanks

Hmmm….. I’m not sure what you have going on lol. I inputted a bunch of scenarios into my Shooter Application and nothing is adding up or coming close.

There is a big difference between shooting out to 500 yards vs. 1000. Out to around 500 is easily tweekable, but 1,000 you have to have very precise spot on info entered in to trig. out properly. Your best best is to buy a phone ap like Shooter Ballistics or Applied Ballistics and plug all the pertinent precise info in.

Barrel twist rate:
Twist direction:
Sight/scope height:
Sight offset:
Elevation units:
Turret Graduatons:
same as above for windage:
Elevation correction factor: (this can be used to tweek elev. or if scope doesn’t track perfectly to a 1.0:1.0 Moa ratio)
Bullet diam:
Bullet weight:
Bullet length:
MV:
Velocity variation and powder temp: (if you put in the time for variances)
Atmosphere std:
Drag Model G1/G7:
Zerod range:
Sighted in/Zeroed atmosphere:
Altitude:
Baro pressure: (best to use station pressure if you have a device that captures it, I.E. Range finder, Kestrel)
Temp:
Humidity:

Coriolis comes in to play a bit at 1,000 but the least of your worries now.

Then what you’re actual weather conditions/Atmosphere where you’re shooting at during said shooting session vs where you zeroed in at.

Going from 1,400’ to 9,500’ shooting at 1,000 yards, you’ll have to have most or all the above info to be accurate. A simple elevation change won’t cut it with what info you’re currently using.

Like I said I tried a bunch of tweaking and different scenarios and couldn’t really get close to what you’re actuals are. I tried scope height from about 1.6 to 2.1” (guessing), changed velocities by a couple hundred FPS, changed BC dramatically, changed scope elevation correction factors, tried to guess on your atmospheric conditions zeroed vs will be shooting at etc…. About the only thing I didn’t try was changing your zero yardage. I’m assuming you zeroed in at 100 yards? A lot of pertinent and necessary info missing to get it to all add up.
 

Lrreloader

Well-Known Member
Joined
Jun 18, 2019
Messages
897
Location
Pa
What if the MV isn’t exact and your adjusting for BC when it’s in fact MV’s off? Sorry maybe a dumb question, not sure.
MV shot over labradar single digit
What if the MV isn’t exact and your adjusting for BC when it’s in fact MV’s off? Sorry maybe a dumb question, not sure.
Mv shot over a labradar single digit S.D
 

Lrreloader

Well-Known Member
Joined
Jun 18, 2019
Messages
897
Location
Pa
Hmmm….. I’m not sure what you have going on lol. I inputted a bunch of scenarios into my Shooter Application and nothing is adding up or coming close.

There is a big difference between shooting out to 500 yards vs. 1000. Out to around 500 is easily tweekable, but 1,000 you have to have very precise spot on info entered in to trig. out properly. Your best best is to buy a phone ap like Shooter Ballistics or Applied Ballistics and plug all the pertinent precise info in.

Barrel twist rate:
Twist direction:
Sight/scope height:
Sight offset:
Elevation units:
Turret Graduatons:
same as above for windage:
Elevation correction factor: (this can be used to tweek elev. or if scope doesn’t track perfectly to a 1.0:1.0 Moa ratio)
Bullet diam:
Bullet weight:
Bullet length:
MV:
Velocity variation and powder temp: (if you put in the time for variances)
Atmosphere std:
Drag Model G1/G7:
Zerod range:
Sighted in/Zeroed atmosphere:
Altitude:
Baro pressure: (best to use station pressure if you have a device that captures it, I.E. Range finder, Kestrel)
Temp:
Humidity:

Coriolis comes in to play a bit at 1,000 but the least of your worries now.

Then what you’re actual weather conditions/Atmosphere where you’re shooting at during said shooting session vs where you zeroed in at.

Going from 1,400’ to 9,500’ shooting at 1,000 yards, you’ll have to have most or all the above info to be accurate. A simple elevation change won’t cut it with what info you’re currently using.

Like I said I tried a bunch of tweaking and different scenarios and couldn’t really get close to what you’re actuals are. I tried scope height from about 1.6 to 2.1” (guessing), changed velocities by a couple hundred FPS, changed BC dramatically, changed scope elevation correction factors, tried to guess on your atmospheric conditions zeroed vs will be shooting at etc…. About the only thing I didn’t try was changing your zero yardage. I’m assuming you zeroed in at 100 yards? A lot of pertinent and necessary info missing to get it to all add up.
I should have been more specific, Im more concerned at 600 or less, I will have no way to verify out west. My father and I have used charts from 1,400 ft elevation that were adjusted to out west elevation with success, but they were correct to begin with. I'm trying to replicate that by adjusting chart at 1,400 ft to replicate my results because I doubt that you can just adjust the chart at 9,500 by same amount of clicks as 1,400 with all the factors that vary from 1,400 to 9,500.

Thanks for all the input!
 

cohunt

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Joined
Jan 21, 2016
Messages
3,215
Location
Colorado Springs, CO
Your actual was less at 300 and 600, but more at 1000 so I'm not sure any adjustments will get you what you are looking for
Are your scope height/zero numbers set correctly?
 

squeeeeze

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Joined
May 21, 2011
Messages
486
Location
Southern Arizona
When I had it at 30 MOA at 1,000 your 300 and 600 are way off. When the 300 and 600 are on or close then I’m showing about 27-28.5MOA at 1,000 depending on how much I changed things but wouldn’t add up. Double check everything and your zero yardage inputted and scope height as stated above because something is off. Is your scope tracking properly? Try a tall target test.

For $10 Shooter is an amazing ap. If you have all the pertinent info inputted into Shooter or a good Ballistic program and your zero environment, then regardless of Station pressure environment/location you should be dead nuts.
 

BrentM

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Joined
Jan 10, 2013
Messages
3,240
Location
Meridian, Idaho
Many of us use shooter due to the simplicity and accuracy of the program. I've used a pile and its one of the easiest to plug and play and lines up with AB quite well. AB is the best engine there is so.....

Now, when looking at a program to calibrate data you have to think this through...... that data has to be spot on to be accurate. There is no forgetting or discounting anything for any reason. So yes, using actual drop data to input for the distance and drop is how you do it. The issue is is that your data for the 1000 is way off. Trying to calibrate and do a semi custom curve is not lining up with that data. Using the 3 inputs the 1000 does not want to correct well. To get to 30 moa it drops mv to 2626 vs 2780. That calibration messes with the 300/600 results big time.

So something is significantly off or missing from the data. My guess is either scope tracking is off, you had a down draft or mirage at 1000, or shooter error. Could be something as simple your zero not being zero'd. You didn't mention zero range so I used 100 for a default.
 

Lrreloader

Well-Known Member
Joined
Jun 18, 2019
Messages
897
Location
Pa
Many of us use shooter due to the simplicity and accuracy of the program. I've used a pile and its one of the easiest to plug and play and lines up with AB quite well. AB is the best engine there is so.....

Now, when looking at a program to calibrate data you have to think this through...... that data has to be spot on to be accurate. There is no forgetting or discounting anything for any reason. So yes, using actual drop data to input for the distance and drop is how you do it. The issue is is that your data for the 1000 is way off. Trying to calibrate and do a semi custom curve is not lining up with that data. Using the 3 inputs the 1000 does not want to correct well. To get to 30 moa it drops mv to 2626 vs 2780. That calibration messes with the 300/600 results big time.

So something is significantly off or missing from the data. My guess is either scope tracking is off, you had a down draft or mirage at 1000, or shooter error. Could be something as simple your zero not being zero'd. You didn't mention zero range so I used 100 for a default.
I didn't shoot that many shots at 1,000 could we remove that from equation, I was told 300 yards and in but want to be prepared for longer since the gun is capable. 100 yard zero, only thing I have to double check is scope height. Using only 300 and 600 values can it be corrected?
 
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