Hey Dave, at our age the Dremel saves on the arms. I'm not sure what type of steel that is for the thimble rib, but it sure takes a blueing really fast. It turned black almost instantly. I waited the required 1 min time and rinsed. I didn't have to but I gave it another treatment just in case, rinsed, wiped dry and oiled. Maybe I'll be able to sneak out tomorrow and try her out. If not tomorrow, Monday. I'll give the report when I get back from shooting it.