I used to hunt everything with a shotgun, ducks, grouse, woodcocks... you name it, I killed it and ate it. Somewhere along the way maybe 20 years ago or more, I got off the birds and especially waterfowl. When I hunted last it was all lead shot if that tells you anything. I still have boxes of it. Anyway, I have this killer recipe for mallards, teal and wood ducks. I decided I have to server my relatives some duck this year. I don't know anything about all this new shot. If I used to use 5's and 4's... what do I replace them with today. I'll be using an old Browning with a modified choke, 2 3/4 inch shells. I gave my nephew my full choke model 12. What do I need for puddle ducks on a pond.
If you were shooting 4&5 shot lead, I would lean towards 2 shot steel.... Know there are some other great alloys (like HEVI-Shot, Tungstun, etc) out there but they are to expensive for my blood...
I like Kent Fasteel in a #3 or #4. If your a little rusty with the shotgun you might load 4,3,2 in case you have to reach out there past 50 yards. Also it would be wise to pattern because lead and steel fly different. Mod or improved cyl choke work best for me.
I do well with 2's for ducks out of an imp cyl. Steel tends to hold a much tighter pattern so you dont want the tighter chokes. Also, since it is lighter than lead it has less knock down power at farther ranges. For that reason, we like to use the higher fps loads. The old saying around here with steel is, "speed kills." Dont buy the cheaper, slower loads. The faster loads will hold penetrating energy longer. If you are in tight quarters like a small hole for woodies and have birds that will work close over decoys, you can even do well with 4's. Enjoy your Fall chasing ducks and deer.
Early season when they are not heavy feathered yet I like to use #2 shot in the 1500 FPS range. Late Season birds that are heavy feathered I will go to #BB shot again in the 1500 FPS range.