I have used the 45 pads on dozens of guns. Absolutely no problems.
I like to put a coat of Ballistol of the barrels and let them sit for a couple of hours then go over the barrels with the 45 pad followed by a good rub down with a terry cloth towel.
Can't say I tried it on cold blue barrels but no big deal if it removed the bluing as its simple enough to redo with a bottle of cold blue.