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(Copy and paste link into URL box)
http://www.google.com/cse?cx=011358298806334250876%3Atgu2trurtro&ie=UTF-8&q=20+ga+duck&sa=Search&siteurl=www.shotgunworld.com%2Fbbs%2F&ref=&ss=4298j2977532j10#gsc.tab=0&gsc.q=20%20ga%20duck&gsc.page=1
Wyogal most certainly you can afford hevi shot you just have to be like me and shoot less than 25 shells per year.
