Ok, the file is good then. That one value might be missing because you haven't turned USA on. Try to turn on USA in-game and see if it shows in the config file.
It's explained down in the notes:
Note that this is the Scaled Iron Sight, meaning the "Field of View Scaling in ADS" option is enabled.
This calculation require the following settings:
GstInput.MouseRawInput 1
GstInput.SoldierUniformAiming 1
GstRender.FieldOfViewScaleADS 1
In other words, if you have FOV Scaling on, use the scaled calculations, if it's off use the others.