The only disadvantage to Zinc plated steel shot is it isn't copper plated lead shot. In other words,your on the right track. Go over to Duck Hunting Chat,join and get on the reloading forum. Those guys know a bunch and thrive on that stuff.

 

The only problem I have with it, is that you have #1's. Your gun will either pattern it or not. I went through 20# of it trying to find a load that would pattern decently in my guns and finally gave up and went to #2 and #3 pellets. Zinc plated is nice. Especially if you hunt salt/brackish water. DHC is a good forum for waterfowl info.

 

These Fellas are spot on with using Zinc plated shot but all I can add is ,
I shoot 1's and 3's out of my Invector Plus guns in 2 3/4" loads and I see no
reason to change , they do seem to not pull much feathers into the birds like
unplated shot .

 

RSI 65 with a SAM1 containing 450 gr. of #1's is a favorite. Lethal out of proportion to the short 2-3/4'' Fed GM hull. It's a load that just works. I'm indifferent on the zinc plating. Some of my loads contain it, some doesn't. They all go in the same bucket.