I think if you want to outlaw lead for upland hunting, go out and harvest the wild birds and study them. See if there is any impact directly to the point.
Do a study directly on the wild birds harvested during the hunting season for example. It should be easy to harvest the gizzards and the liver at the game check points.
My common sense tells me that the results will show no significant impact of lead on the health of the birds. But I can be grossly wrong. I would accept it should I see the PROOF.
But when you come up with such proposal and claim studies that don't have much relevance to the current topic I will not accept it. It is ludicrous.