RE: Magnum shells?
3" number 2 black clouds the whole season for ducks and geese. Only time I would shoot 3 1/2" is if I get a blind at pymy and I know those birds rarely decoy, plus after the first few days and them getting sky busted on them birds stay just out of range of most people and ammo (I just switched to the black cloud 3" snow goose for these situations even).
I don't think I'll ever shoot 3 1/2" again for waterfowl, and now I'm probably even going to use the new black cloud high velocity in 3" #4's for turkey even.
The worst day hunting or fishing will always be better then the best day at school or work!