The Italian maker, RC, loads a 25gram 20gauge lead #7 [.100"] in their special 'Competition TRAP' rounds. It utilizes a highly polished round shot that is the most uniform I have seen. I suspect the shot must be roller milled to be as perfect as it is, but don't know that for a fact.
I've used it pass shooting pigeons/dove in South America w/excellent results & it is my ammunition of choice when the outfitter can supply it.
Unfortunately, I am not aware of it being available here in the states. It is very high quality ammunition made specifically for shooting trap with a 20ga. And it is 25grams & not 24 like mandated for use in the 12ga. for bunker.