I was a little scared of the nickle plated scratching the barrel.
The main key to shot scratching a bore is whether or not it is soft enough to "give" at ignition set-back time, and/or as it's being compressed going down bore and through a constictive (modern) type choke. As long as the core of plated shot is made of lead which will "give", there's no problem.
NOTE: Caution against possible thoughts of buying/using copper plated BB's (for an airgun) because they are copper plated steel, not lead.
EcoTungsten is a specially made material that acts exactly like lead and can even be used bare bore in old original damascus barrels.
I've probably used a good 150+ bare bore shot loads for pattern testing with copper plated, nickel plated, and EcoTungsten(Niceshot) types of shot in my .28ga and .20ga Flint smoothbores...not a mark on the bores at all.
Final suggestion:
If you decide on copper plated shot...work hard to find some old bag(s) of Winchester Lubaloy (copper plated) shot...hasn't been made in a few decades but was the king in the first half / two thirds of the 1900s...true "plated" chilled shot...not the copper plated (wash) junk made by Lawrence...otherwise pay a few dollars more and use Nickel plated as it's better.
But the Winchester Lubaloy is the real deal if you can find any left over bags...old hardware stores, garage sales, estate sales, etc...I still have a half bag of #4's that I use from very sparingly...nothing beats the old Winchester Lubaloy.