Yes I agree, I have been taught that "tuning" a lock or action on a firearm, means more than polishing surfaces, it means adjusting the sear interface, and in the case of flintlocks, adjusting angles on the **** jaws when needed.
I was also taught that when one is not
trained how to do that adjustment of the sear and tumbler on a muzzle loader lock, NOT to attempt it. The reason being it is amazingly simple to remove a tiny bit of metal in the wrong place to render a lock that has difficulty working into a lock that will not hold full ****, and requires then a lot more work and probably replacement parts.
One thing I've learned is that a great many folks mis-diagnose the lock problem. I often hear, "My spring is too strong", when in fact what really is wrong is "my parts are too rough". The results I've seen is folks who grind off the side of a leaf spring, only to ruin it, when that wasn't the problem.
There are parts on a flintlock,
especially on factory made locks, that may be polished by Joe-Muzzleloader, without FUBAR-ing the lock. The easiest that come to mind are...
the interior surface of the lock plate where the mainspring touches,
the edge of the mainspring where it touches the lock plate,
the upper surface of the frizzen spring where it touches the frizzen-cam, and where it touches the lock plate,
the frizzen cam where it touches the frizzen spring, and...,
the sides of the frizzen where it touches the lock.
ALL of these areas may be
polished by hand using emory paper and some oil, to get a much smoother are where the surfaces meet, often do a world of good. They also don't run the risk of screwing up the part.
LD