Vintage waterfowling has really become the realm of the handloader.
It is probably best to partner up with someone and split the cost of a few boxes.
The choices just keep getting fewer and fewer. And even if the shot is vintage friendly non-lead, then the cartridge pressures are still SAAMI max. Or the velocities are so high the recoil beats an old stock to pieces.

I have read where the cost of Bismuth has come down enough to warrant the making of shot again. But I'm not holding my breath.

Out there doing it best I can.