I "think" the flint sparking question came up some years ago on here.
I don't remember what the outcome was.
Maybe somebody could volunteer to take a stainless RMK and a ferro rod, and a piece of natural flint, and run a test?
Of course, we don't want to damage a safe queen....
So maybe a heat-treated blade blank at the shop...?
Larry
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Larry W. Williams
RKCC #CM-041
ABKA #046
RKS #1246