App differs from reality; what parameters to adjust

[Carl A]

Berger 300 Elite Hunter in 338 lapua magnum. According to 2 different labradars V0=890 m/s / 2920 f/s. (89,5 gr VV 570, 80 cm, 31.5" Krieger Barrel)

Bergers app and JM Ballistics; It is quite obvious (great accuracy in the shooting!!); At 200 meters apps= reality, at 3-500 meters I have to make 1 extra click at my scope and slighty above 1000 m I have to make 2 extra clicks.

What parameters should I adjust to get the app=reality??

Next week I am to attend a competition shooting up to 2000 m, and I have no opportuity to test shoot any distance near that before...

 

[JC0352]

What parameters should I adjust to get the app=reality??

I’ve had good luck manipulating the BC to get my app to line up with reality on the target.

I believe in some of Frank’s earlier podcasts, he mentions tweaking velocity a little for about out to 600yds, then BC for further out.

 

[Carl A]

Thanks Pal!! - beyond 600 yds, when tweaking BC should I set the velocity to the measured, 890 m/s, or to the lower one I tweaked to to get it correct up to 600 yds?

 

[rjacobs]

Maybe I am weird and I dont take those apps/range cards as "gospel"... I take them as a starting place, then I go to the range and verify... Like you are finding, I find them .1 or so off at longer ranges. I simply make note of where I was .1 or .2 off and when I get home I adjust my dope card and print a new one out, re-laminate it, and hang it on the rifle.

 

[JC0352]

Thanks Pal!! - beyond 600 yds, when tweaking BC should I set the velocity to the measured, 890 m/s, or to the lower one I tweaked to to get it correct up to 600 yds?

I would ensure you have the same atmospheric conditions in there as the day you last shot, then play with velocity and BC until your app or whatever lines up with your actual results at all ranges.

 

[Lowlight]

Honestly, a click or two is nothing to worry about, that is less than 1 MOA, if I am within .2 I am good

You tweak MV at 600 and BC after in order to balance it out, but if you are within a .1 of something why sweat it, call it good, you're not that accurate to worry about it.

Most targets are a lot bigger than that, you'll just end up chasing your tail

 

[Carl A]

of course testing irl is da shit. Which I have done up to 1000 m (at a certain atm cond), so that distance is no big issue. - The issue is at what clicks to start shooting at the competition beyond 1000 m. (hopefully I might get a clue before the 2 km shoots since we will shoot at 555, 1107, 1434, 1635 and 2023 meters)

 

[Danattherock]

Manually lower your BC until the software shows what you need to get center hits. Sounds like the BC you are using is overestimated. Frank had a great article and perhaps youtube video a few years ago, the disconnect between you and your dope, or similar. Would be very interesting read if you can find it.

 

[Pink_Mist]

AB app tweeks the MV to calibrate prediction to actual correction. I do not mess with the BC at all because I cannot. When you purchase the proven curves that Applied Ballistics offer you can safely rule this out. I have found the best luck with calibrating right before transonic if possible. If you cannot then obviously see where you are at the max distance you can shoot, then 300 yards before that and again another 300 before that.

I have made a chart with Excel with 0.0 mils down to 15.0 mils in .01 increments. Then across the top with yards in 10 yard increments. This is a huge chart. Every time I go shoot I am also filling out a form with predicted vs actual data. I fill in my Excel chart. I keep each entry a different color and store that data as well. This would be the atmospherics. It is easy to see after a few sessions that filling in the blanks from 0 to 1200 yards that I no longer need a ballistic solver for all conditions. The farther out the target the disbursement obviously increased do to the compounding factor however. This is how and why I do this, I can shoot any distance out to 1200. I use the correction that falls in the middle of the spread and I get a hit. If I hit high or low dictates how I correct for every other target that is closer. I can get hits with one set of data three season out of the year out to 1150 with a 6.5 creedmoor. Using this actual dope in a visual chart has done more for me than ballistic apps ever have.

 

[Colorado S14]

I believe that @lowlight has said he adjusts velocity inside 800 yards and then using that velocity trues using BC beyond that. I am sure Frank will chime in at some point to correct me, lol.

 

[Pink_Mist]

AB app tweeks the MV to calibrate prediction to actual correction. I do not mess with the BC at all because I cannot. When you purchase the proven curves that Applied Ballistics offer you can safely rule this out. I have found the best luck with calibrating right before transonic if possible. If you cannot then obviously see where you are at the max distance you can shoot, then 300 yards before that and again another 300 before that.

I have made a chart with Excel with 0.0 mils down to 15.0 mils in .01 increments. Then across the top with yards in 10 yard increments. This is a huge chart. Every time I go shoot I am also filling out a form with predicted vs actual data. I fill in my Excel chart. I keep each entry a different color and store that data as well. This would be the atmospherics. It is easy to see after a few sessions that filling in the blanks from 0 to 1200 yards that I no longer need a ballistic solver for all conditions. The farther out the target the disbursement obviously increased do to the compounding factor however. This is how and why I do this, I can shoot any distance out to 1200. I use the correction that falls in the middle of the spread and I get a hit. If I hit high or low dictates how I correct for every other target that is closer. I can get hits with one set of data three season out of the year out to 1150 with a 6.5 creedmoor. Using this actual dope in a visual chart has done more for me than ballistic apps ever have.

Frank liked what i said... im blushing.

 

[Lowlight]

Ya you can’t tweak a custom curve so it’s MV only unless you have the range to go beyond transonic

but I don’t use CDM and honestly I tend to use a lot of G1 cause I know them, but I adjust MV at 800

then BC at 800 to fine tune, or if it needs it further I can tweak out

the MV changes things close so once that is set you adjust BC to not change 4, 3, 2, etc