A bird, clay or feathered, moving at 50 MPH, is moving 880 inches per second. A load of #8 shot, starting with MV of 1155 fps takes .1367 seconds to the 40 yard mark. Start it at 1255 fps and it takes .1449 seconds to get there. During the time of flight difference between the two loads the bird moves 7.2 inches. That's the difference if lead required.
The difference between MV is about 8%, time of flight difference is about 5.6%. Difference in lead required is 5.6%. As 2 piper said, it's the time of flight that matters, not the muzzle velocity. I though everyone knew that. Obviously not. The point of this thread was, and is, that hiking up the MV does not make the drastic difference in leads that many people think. It is also a fact that the difference in TOF is less at 40 yds than it is at 20. Of course I used a calculator, and verified the answers with a slide rule made by S & R Enterprises and sold for just this purpose. That's the way facts are established, not by a shooter's perception, or old wives' tales.
