Hollow 355 cats

I have an old set of cats that I've removed the ceramic core from. All of the ceramic core comes out fairly easily but it leaves a metal band inside the cat that rattles.

What are the tricks to stopping that rattle?

In a perfect world I'd like to get the band out, Has anyone done that? Without cutting the core apart and then welding it back together.

Another option is to simply go down inside the cat with a welding rod and put a few tack welds in place to hold it in one position.

Any ideas that I'm missing?