I've been testing the Kestrel with a specific load I constructed for my Weatherby .257 Magnum Vanguard rifle. The 100-grain Barnes TTSX bullet has a measured velocity of of 3,483 feet per second from my Vanguard rifle. From Barnes, I know that this bullet has a ballistic coefficient value of .357. I enter this information into the Kestrel, along with velocity, bullet weight, bullet length, and bullet diameter. Then, I allow the unit to take a snapshot of current atmospheric and wind conditions. A fraction of a second later, the Kestrel displays a shooting solution based on the yardage I select. The Kestrel provides not only elevation data to account for bullet drop, but windage adjustment based on the current wind strength and direction vector. It’s somewhat of a miracle.