I've done a bit more reading and a few calculations I'm even more confused now
It doesn't sound right that the pellet leaves the barrel and instantly travels at 5mph - you chaps are right, I'm being an idiot.
If it did then the amount of wind would be dead simple to calculate - it would just be the time of flight times the wind speed. The actual calculation is a lot less than that, so I must be wrong.
The calculation takes the difference in time between how long the pellet actually takes to reach the target (using BC, drag retardation, etc etc) and then the time it would take the pellet to hit the target in a vacuum is subtracted from that time. That difference in time is then multiplied by the wind speed to give the drift figure.
So, yeah side profile of the pellet isn't included in the calc and I have no idea why the speed of the pellet in a vacuum is important.
I've gotta throw my hands up in the air and say - I don't bloody know
Maybe taking away the time of flight in a vacuum is just an approximate way of figuring out how long it takes for the pellet to accelerate to 5mph??
But that seems dodgy to me. I know a man who knows a man who knows as much about this stuff as anyone in the world - I'll see if I can get an answer from him. (but if I do, I probably won't understand it)
For the purposes of this thread though, I don't think it matters (it might, but I don't think it does). Because it's still going to be true that if a pellet spends less time in the wind, it won't take as much wind.