Just an amateur who reads everything I can find out there,
and what I found was...
Winchester came out with copper plating first...called it lube alloy.
Supposed to help with reducing friction.
Even so, copper plated 22lr has a hard wax coating that does the real job of reducing friction.
Now copper plating is used to make for more attractive cartridges and improve sales, not accuracy.
Folks see shiny copper and think centerfire, then think it'll make things better.
The problem being the copper is plated over an already beat up lead core/bullet.
Do you think with the cartridges below, the copper will improve accuracy?
Hard lubricant is intended to minimize dirt from sticking to the bullet
also to limit lubricant build up in semiauto firearms.