No contest the majority of advice (rightly so) will be in favor of the 1oz #3 steel loads for ducks. For geese it get more difficult 1oz #2 you might get to pattern well but so few of a small shot size requires decreased range. 1oz of #1 steel most likely will not pattern well at all. So that leave heavier than steel shot which the only commonly available factory loads would be from Hevi Shot either #4 or #6.
There has been a lot written on various forums about using the 20ga for ducks and with both steel and HTS shot.http://www.duckhuntingchat.com/forum/viewforum.php?f=14
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Wyogal most certainly you can afford hevi shot you just have to be like me and shoot less than 25 shells per year.