Them nickel plated shots are the killers, I've used them in #2 on geese and you can tell the difference.
I just got back from a three day shoot in Quebec. The mallards and black ducks were thick there as well. Unfortunately I had to shoot Kent TM instead of nickle plated lead but it was #5 shot at least and kills them canards right dead.
The three of us had our 6 bird limits everyday. I had a banded mallard drake and a banded goose and Mista Kaas had two banded drakes as well. We were all shooting Parkers but did talk about a 3 inch Smith 12 gauge that Russ has at least. *wink*