I used Laurel Mountain solution to rust brown a barrel for a flintlock for my son a few weeks ago, I was surprised that
the bottle didn't come with instructions, but found them online here


Laurel Mountain instructions

I was pleased with the results, that being said, there is a big difference between a flintlock barrel and say a set of damascus barrels,
if you want, PM me with any questions you might have, I will try to help.

Fred