Range Report Using DA with JBM

[distantfoe]

I've gone back over a lot of threads concerning density altitude and still don't understand what to enter into JBM.

Correct me if I'm wrong but shouldn't I;

set temp to 0
set altitude to 0
set pressure to 0
set altitude to what my kestrel tells me for density altitude
check std atmosphere at altitude
UNcheck pressure is corrected

 

[Niles Coyote]

Re: Using DA with JBM

Tagged for later reference, have you read through this by Lindy?

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/Baro/

 

[coues7]

Re: Using DA with JBM

I believe Lindy specifically mentions using JBM with DA. I think Zak Smiths article on Demigodllc talks about it as well.

 

[rmfield]

Re: Using DA with JBM

If you are trying to compute data for the exact temperature, pressure and humidity for your site, don't use density altitude.

Just plug the actual temperature, pressure and humidity in.
Set altitude to zero and don't check the boxes.

To create a series of data tables for various reference Density Altitudes, plug in the ICAO Standard Atmospere (temperature, pressure and humidity) for the DA that you want data for. Set altitude to zero and don't check either of the boxes. Then, use the DA reported by your Kestral to determine which table to use.

 

[DaveV]

Re: Using DA with JBM

Go with Lindy on this one

 

[rmfield]

Re: Using DA with JBM

Dave, are you suggesting that my post is bad advise?

 

[c ward]

Re: Using DA with JBM

This is probably more germane to the posted topic since everybody is jumping on the Lindy bandwagon , http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/DA/ .

The question to ask is where the ICAO table in Lindy's articles came from and just maybe that guy was posting here already .

 

[distantfoe]

Re: Using DA with JBM

Great information. I'm really wanting to produce some ballistic tables to cover a variety of conditions. Just trying to filter through the different methods as I don't have a mobile calculating device with the exception of a kestrel 4500.

 

[Tburkes]

Re: Using DA with JBM

Have you seen this link? If you own a Mildot Master, you already know how to use this. Of course it's only for .308 at this time.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2004610#Post2004610

 

[rmfield]

Re: Using DA with JBM

Great idea. Many of us do it that way quite succesfully. Its a little complicated at first, but easy once you get the hang of it. You can prepare the tables on a desktop computer/printer in advance for each 1000' of DA. Then just use the Kestral DA output to choose corresponding table.

PM if you get hung up on anything.

 

[DaveV]

Re: Using DA with JBM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rmfield</div><div class="ubbcode-body">Dave, are you suggesting that my post is bad advise? </div></div>

No, my post was not directed at you. I'm just saying that Lindy has brought the most to the table when discussing DA. The important thing is that DA boils the important externals down to one usable number.

 

[runngun]

Re: Using DA with JBM

If you click "std atmosphere at altitude" it ignores the temperature, pressure and humidity boxes, and uses the ICAO standard for the elevation entered.

So for DA tables, just check the "std atmosphere at altitude" box, and set the elevation for the DA you want.