Note that most stainless used in guns is rust resistant, not rust proof.
"300" series stainless alloys are very nearly rust proof, but don't respond to heat treating, so their mechanical properties are limited. These alloys are used a lot in cookware.
"400" series stainless is only rust resistant, but it DOES respond well to heat treating, which is why these are used in guns - 416 is fairly common. (The "465" stainless that Ruger switched to in their .454 SRH is said to have a corrosion resistance that "approaches" type 304 stainless . . . )
There are other, newer, more complex alloys as well, but 300- and 400- series alloys are the most common.
I would not use ordinary steel wool to buff a stainless gun for reasons already mentioned (and debated) in earlier posts.