You can't measure velocity over a long enough range to get an accurate BC with a commercial radar system. Either use the box BC and tune your solution using measured drops or use something with AB's calculator and use a CDM. CDMs are produced with a much larger radar system that costs tens or hundreds of thousands of dollars, and can track bullets to several hundred yards.
It's useful to provide a starting point for bullets that don't have a listed BC. I use my Labradar to calculate BC for cast bullets and it's reasonably close. It's not better than what's listed on the box for anything else.
