Artie, you ask if anyone ever measured the velocity down range? Under normal conditions, that can be calculated very closely if you have the BC. Of course, you'd also have to adjust for altitude as I do here at about, 3500 fas. This said, you could use a Labradar and do it yourself. Hard Air Magazine is in the process of using a Labradar to calculated (or proving) the BC of a whole range of pellets. I notice their data doesn't agree often with published data, but then again I don't know what their altitude is.
As an example, I'm in Roswell, NM at 3,500 fas. The JBS, .25 caliber, 25.39 ground pellets have a published BC of .036. At this altitude, the BC is .042. And, typically the humidity is rather low during the Summer time, along with high ambient temperatures. All of these factor change the effective BC.