Corrected pressure in JBM trajectory software

[andrewctillman]

I am confused as to check or uncheck the pressure corrected (or absolute) box when using Bryan Lits trajectory software.

It makes a huge difference at 1000 yards (3 MOA).

I check local weather data before shooting at long range. Temperature, humidity, altitude.

Is weather service data corrected or absolute?

 

[.300winmag]

I am confused as to check or uncheck the pressure corrected (or absolute) box when using Bryan Lits trajectory software.

It makes a huge difference at 1000 yards (3 MOA).

I check local weather data before shooting at long range. Temperature, humidity, altitude.

Is weather service data corrected or absolute?

The pressure reported by weather stations is corrected pressure, so you will need to input the altitude of where the weather station is into the calculator.

Absolute pressure is what you would get from a Kestrel, when you use absolute pressure there is no need to input the altitude in the ballistic calculator, you leave it set to 0.