RE: omega stainless steel barrel
asianhunter.. what rifle are you talking about? If it is a Thompson Center Omega then it is stainless steel if the box says so. Same as if it were a Knight Rifle. Some of the rifles might look like Stainless Steel such as a CVA but most of the time they have a Nickel finish.
That magnet test I am not sure if it would work or not. If the box said stainless steel, I am sure it would be stainless steel...
Good luck with your rifle.