Frizzen- Telling Hardness From Appearance?

[Ray-Vigo]

Is there a way from appearance to tell if the frizzen is not hard enough? I have a fowler with a frizzen that I would describe as "OK" sparking, not great, but not not terrible. It does not unduly eat flints, though I don't think it sparks quite as well as my other locks. The flint made what I would describe as somewhat deeper impacts than I have on my other guns. I do realize you get some "impact lines" from the flint, but I'm wondering if you can tell if it's too deep/soft from looking at it.

[P.W.Berkuta]

Hard for me to tell from your two pictures as to the degree of 'ruts" in your frizzen.  I know the two pictures are of the same frizzen - the top picture looks totally chewed up but the bottom picture does not look as bad. If I were to take a GUESS from those two pictures I would say the frizzen is a bit soft. This is only MY guess from your pictures which does not mean much

[retired fella]

If this has happened over a number of years I suggest that you grind it smooth with a dremel stone and don't worry about it.  Your statement that it is not hard on flints tells me that it couldn't be too soft.  I occasionally polish my frizzens and works well for me.  Sparks like a Zippo lighter

[D. Taylor Sapergia]

When a frizzen becomes gouged out, I put them against a 6" grinding wheel and slowly take away the gouges.  Frequent quenching.  Put your thumb on the back of the frizzen...it'll tell you when it wants quenching.  A frizzen will usually take three such 'grinds' before it needs replacing...abut 15000 shots. 
If I may, it is an observation of mine, based purely on supposition, that we shoot our flintlocks much more than original rifles were shot.  Some of us shoot between 50 - 80 rounds every weekend from our favourite rifle.  I'm guessing that 18th C middle class men and women did not.