Why is the 8 bore illegal for waterfowl/migratory game?

[charlie cleveland]

ray i bet that winchester kicks pretty good shooting that heavy of a load in a 12 ga...ive shot up to 3 ounces in the old 8 ga f a loomis...the old 8 kicks pretty good with this load...my old 8 is choked about modiefied...the closet thing in shot size ive got at the moment is a load of no 6 s lead in 2 1/2 ounce load...i dont think my 8 will beat your score of 70 to 75 pellets at 70 yards but im gonna try this load after a while will post results tonight...i will step off 70 paces and i will take long steps if my gun shoots any were near yours i will then measure the distance..my old 8 ga really patters better with large shot than small...well im off to try that 10 inch circle... charlie