I have rust browned barrels then put them in boiling disilled water to turn them black, or blued . After carding and doing tjis prosees 12-20 times I cure it in baking soda and water with a cold water rince . Then to seal it I heat up the barrel with a heat gun and apply bees wax . Never had a problem with early wear ...
Thats why they call it hunting and not grocery shopping
Hoppe's #9 is great for preserving metal and blued surfaces. I have always wiped my guns down with Hoppe's after cleaning them and the bluing on all of them looks new, even my '94 that is 39 years old.