Electro, or Electro-less
Copper is only used in Electro plate Nickel, used to provide a conductor
for the nickel to adhere to. Electro-Less Nickel does not use copper as a
base. The part about hoppes potentially undermining the coper base is
correct but there would have to be some area where the copper was
exposed, and then you would literally have to SOAK the parts in it for
a matter of hours. With not expose areas even electro nickel would be
would stand up to repeat endless cleaning. Fortunately, the modern
way of doing it is Electroless, which does not have the same weakness.
My Uncle owns a very sucessful plating business in central florida, that
does defense work. He is also a gun enthusiast, and has tested his
nickel jobs extensively with prolonged Hoppes baths (several Weeks)
and had no failure. He plated one of my rifles, and I can tell you
that in all the years I have owned it, and cleaned it I use hoppes
exclusively, with no problem. My father also owns an older S&W
topbreak, with elctro plating, that has been cleaned with hoppes
for the last 25-30 years with no problem. Unless you have an Electro-plated
gun with an already damaged finish, you truly don't have any thing to
worry about.