I purchased a 72mm - 77mm adapter ring and cut a piece of polycarbonate (Lexan or Lucite, can't remember) and epoxy glued the protector into the ring. I've fired onto the ring point blank with nary a scratch nor dent.
I got the idea from Big Tom (Agit-Prop). Tom, do you have pics?
Quaestores supervised the financial affairs of the Roman Republic's armies and officers.