I've used it for a decade now in turkey hunting, and consider it by far the best shot for that use. It's also great as a predator load. I dropped a coyote last week at 50 yds with a one ounce load of #8.
I am not much of a duck hunter, but I have tried it on ducks and I don't think it is worth the trouble or expense. The one ounce load of #8 in a 12 gauge gun patterned at 87% through a cylinder choke. That's way too tight for my shooting skills. But I'm a guy who is lucky to get to go duck hunting 5 times in a season, so someone who is serious about it might reach a different conclusion.
From all that I have read, I think the best use of TSS for waterfowl is probably in a duplex load with steel in a smaller gauge gun. A load like this might make you more effective with a 20 gauge gun.
If you are serious about trying it, do some reading on this site:
https://pipesf16.wordpress.com/tss-steel-duplexing-when-is-steel-enough/The guy who owns this site has done extensive testing of it and is worth reading. Good luck with it.
