I cast Alley Cleaner 473 gr as solid, 400 gr large HP pin. I size to .500 and shoot 1400-1500 fps. The alloy is WW equivalent and the solid version water dropped. HPs were air cooled. I get significant leading with the both.
How does it shoot for you?
There is only one small lube groove. Is it enough lube? I am using White Label BAC. Maybe I should add a PVC disc as a wad. Do you use wads? I am yet missing a .500 size punch to make them.