Dear Ruslana, I can't offer much help with the jump ringer problem but I may be able to save your piece of chain mail. I had the same problem and I put mine in a cheap tumbler with pumice powder and after a couple of hours the mail was fine to wear.
Pauline, Thank you for your suggestion. The reason it works so well is
that the burs are so thin and fragile. I’ll be sure to pass this along
when asked the same question in the future. Incidentally, pumice powder
is also used commercially to polish small acrylic (plexiglas, perspex)
parts. Tumbling is done dry with a minimum of two parts pumice to one
part work by volume. Run the tumbler 24 hours a day for a week.
Ray Grossman Inc.
Manufacturers of Jump Ringer