Back to your original problem of rough edges… I assume you are using 1/8″ fiber paper to line your stainless rings?
Try using Papyros as the first layer of fiber paper that touches the glass. It leaves a very smooth finish that requires much less coldworking than regular, rough fiber paper.
Papyros is Spectrum’s answer to Bullseye Thinfire — it holds up a lot better than the Thinfire (you can usually remove it from the kiln in one piece, where Thinfire basically turns to powder)
Jester’s Baubles Fused Glass Designs