Canvasback ducks can go 70mph. I shot a many one of them in my youth and was always amazed how fast a big duck could fly. Teal can hit Mach 3. Well that what most hunters think. In fact they are among the slowest at 30 mph. Decoying ducks are often coming in a less than their maximum speed which is 30-70mph. Canvasbacks being the fastest. I picked 40 as a rough average. If f they are coming in slowly they might be 20-25 or less and some might be over 40.
Teal with a tailwind do seem twice as fast. Even better are late season mature Dove with a good 25-30mph tail wind. They can hit some truly impressive speeds.
But the math is the same. At 20mph the distances traveled is half the 5.86” and at 80mph it is still under a foot at 40 yards. And shit string only theoretically works for you if your are in front of the bird. If a fringe part of the pattern of 5” makes much difference you most likely should not take the shot. I’d rather not shoot instead of crippling a bird. And the outside 2-5” of your pattern almost always sucks when you look at it.
