I think you can shot any non-toxic shot out of it as long as you keep the choke to modified or more open (e.g. IC). I'm coming around to the point that it's best not to over choke for most birds we typically hunt.
I go with faster hevi steel or tungsten for heavily feather northern ducks and geese. But I've shot plenty of ducks with straight steel 1 1/4 oz + faster the better for me. Each finds what works best for them the way they shot and the shotgun.
Try patterning several different loads and chokes at distants you think you'll likely to shoot most at and it'll give you