Stupid Question About Kestrel

Measuring the wind speed with the Kestrel is a starting point. You have to get an idea of what the wind is doing over the path your bullet is going to take and include those effects as well.

A better use of the Kestrel is to measure Air Pressure, Temperature, and to a lesser extent, humidity. People tend to look at the composite number formed from these called Density Altitude. Basically, it's the air density that the bullet will be passing through.