BOOGIE... you can make your cases from free machining steel, & even stainless ( I have a unique cartridge & gun, 22 magnum centerfire... kind of a cross between the old Velodog cartridge & the Cooper Center Fire Magnum ) I lave machined cases that are steel & some that are stainless... sorry, cant suggest an alloy of brass though
Stainless cartridges would be very cool. Only thing is that machine time and SS are on the pricy side in that case. In an instance like you have the cost isnt an issue. Post a pick if you have a chance.