Wresting with specifics for zero height and zero range entry in JBM and a couple of apps (Strelok, Trasol), where I've been running some numbers for comparative purposes.
In the JBM trajectory calculator page, there is a field entry for zero height - which is defined as 'the height of the zero point at the zero range'.
Related to this, the JBM zero range field entry is defined as 'the range at which you wish the bullet to cross the line of sight'.
In relation to zero height, I believe I enter the height above or below the aiming point at which the POI (group) formed? e.g. 0.1 mil high at 100yds?
If so, do I put in the zero range field:
1. the distance I actually zero-ed at (e.g.100yds), with 0.1 mil high entered in the zero height field, or
2. the distance at which I wish the bullet to cross the line of sight (e.g. 150yds - because I want, for whatever reason, a zero at that distance)? If it's this, do I still put in the 0.1 mil high zero height? I'm assuming not, as the calculator has no field for me to enter the 100yds actual range I zero-ed at, 0.1 mil high, so the software can't account for this?
The whole wish (want) definition vs actual zero range has me a bit confused. Doing one or the other per above introduces a compounding deviation in projected elevation.
I know this is probably way down in the weeds - but a couple of little errors in data entry here and there and you end up with garbage output and excessive head scratching.
Rabbit holes...
In the JBM trajectory calculator page, there is a field entry for zero height - which is defined as 'the height of the zero point at the zero range'.
Related to this, the JBM zero range field entry is defined as 'the range at which you wish the bullet to cross the line of sight'.
In relation to zero height, I believe I enter the height above or below the aiming point at which the POI (group) formed? e.g. 0.1 mil high at 100yds?
If so, do I put in the zero range field:
1. the distance I actually zero-ed at (e.g.100yds), with 0.1 mil high entered in the zero height field, or
2. the distance at which I wish the bullet to cross the line of sight (e.g. 150yds - because I want, for whatever reason, a zero at that distance)? If it's this, do I still put in the 0.1 mil high zero height? I'm assuming not, as the calculator has no field for me to enter the 100yds actual range I zero-ed at, 0.1 mil high, so the software can't account for this?
The whole wish (want) definition vs actual zero range has me a bit confused. Doing one or the other per above introduces a compounding deviation in projected elevation.
I know this is probably way down in the weeds - but a couple of little errors in data entry here and there and you end up with garbage output and excessive head scratching.
Rabbit holes...
