Well, you're sorta backing into it here. TOF is the first step in determining BC, but you can also do it with two velocities at different distances as well. You have to remember, velocity IS TOF over a measured distance, and nothing more. What we're measuring here is drag deceleration, or how much velocity the bullet in question is shedding over a given distance. If you use the tables themselves (and you can find the Ingall's tables--roughly equivalent to the G1 drag model--in Hatcher's Notebook) you'll see there's both a time and space function. He also explains in detail how the calculations are done, and you can do your own. It's not difficult, just a bit tedious. Personally, I think everyone should at least give it a try, so they have some idea of what's involved rather than just punching numbers into a computer. Sort of like learning to do math WITHOUT a calculator, before you start using one for all your math problems. It just gives you a clearer understanding of what you're looking at, rather than what may seem like a bunch of random numbers.
I think part of the problem that we're dancing around here is the fact that TOF would be drastically different, depending on what part of the bullet's flight you measured it over, how far it was measured, etc. . Drag deceleration and velocity loss is anything but constant. It changes substantially, with the greatest percentages of loss occurring at the highest velocities, and becoming much less as the bullet slows. Remember, atmospheric resistance is roughly proportional to the square of the velocity; halve the velocity and you've reduced the resistance by a factor of four. Double the velocity, and you roughly quadruple the resistance. Using BC, and an appropriate drag model accounts for this, and will give more accurate calculations at all distances of the bullet in question's flight.
Whew! That was a windy one!
