This is not the same thing as the chrome plated bumpers on the Griswald family station wagon.
Industrial hard chrome is very durable.
I hard chrome my IPSC pistols and the finish is amazing
Chrome lined bores are common in M14, AK-47, M16A1, etc, most military rifles.
Here's what I do.
spray off gunk with WD-40, dripping wet.
or brake cleaner
run bronze bore brush and chamber brush.
run dry patch
clean bore with Hoppe's #9, Butch's Bore shine, what ever you like, using a bronze bore brush.
may let it soak for a bit while I clean the bolt/carrier,
dry patches till it's clean.
I use DEWEY brand coated cleaning rods so I don't mess up the crown.
I make extra sure the chamber and locking lugs on the barrel extension are clean
I strip and clean the bolt/carrier, and lube her up.
I use MOBILE 1 5W30, but CLP, FP-10, or any decent gun oil is fine.
I have read that some strong bore cleaners are hard on chrome, but as long as you don't soak them for weeks at a time, I wouldn't worry about it.
I've been cleaning chrome lined barrels since 1985 without trouble
M16 chamber brush