Lag time is simply the difference between the actual and vacuum velocities.
It represents the differential change under these conditions.
TOF is not liked in the long range shooting community because drift is not drop, and TOF represents drop.
Which just means light wt. lower bc bullets need to be pushed faster,
So we end up with a rule of thumb that works because of the physical limitations of the device being used.


Most people don't have what it takes to get old