Gentlemen,
My comment, for what it is worth, is that in the manufacturing of grip emblems using aluminium based alloys, there was always a possibility of precipitation - i.e. that the aluminium alloy could degrade, or "bubble", and become powdery.
By plating the alloy with copper, this effectively sealed the alloy base, and allowed for the further plating of the nickel finish to be at lesser risk of flaking or lifting - as the copper plating effectively sealed or inhibited the reaction of the alloy when exposed to oxygen.
As a further example of this, a good many of the dress bayonet blades were "coppered" before they were nickel plated - thus ensuring a firm bond between the outer surface nickel, and the under surface of copper plate and base iron/steel.
