I gather (without reading all these posts) that you are worrying about the effects of Sweets 7.62 on a stainless barrel.
I use it all the time on both stainless and carbon steel barrels.
I have not noticed any ill effect on either. (however, I don't leave it in for extended time) only keep patching till no more blue appears,, then flush with inox,, then dry patch.
For what it's worth tho,,,,,,, I have dribbled a bit on a stainless sink once, and it was about 1/2 hr before I mopped it up,,,, and noticed that it was like acid etched.
You can still see where it was.
The big but is,,,,,,,, a stainless sink is almost guaranteed to be of 304 grade (pretty low grade sh!t),, and certainly not the same grade as a rifle stainless.
Hope the above helps allay any fears you may have about Sweets 7.62