Guys:

Would appreciate any help with where I can obtain supply of Italian plated shot (nickel/copper) in #s 4-6 stateside for purchase.

Tom Roster has an article in this months "Shooting Sportsman" where he does hardness testing of various shot. It seems the non plated shot from Precision Reloading is just as hard as the plated shot, and even harder than the nickel shot. I think it was West Coast Brand.
Ballistic Products has nickel and copper washed shot. There is nobody that makes cooper plated shot anymore. Just cooper washed.