Other than Gentry, does anyone make a selection of stainless steel barrel band swivels?

What is the current best adhesive for attachment?

Ruger. Not a big selection.
Solder. but Rugers use a set screw with no adhesive.

Will the heat discolor the stainless.

No but I don't solder those on. Ruger doesn't. I do solder on Talleys as they don't have a set screw.