Sounds like the quick take is 'hand fit & finished to a very high level', e.g., any of the older FN O/U's were hand fit and most quite well .. start pulling the butt stocks off & you see the other part of the def when you realize that from the pigeon grades up they are REALLY 'finished', arguably more so internally than externally.
How many people understand that is open for debate.
Absence of file marks/polish/fit was and in many cases still is the result of tedium, great care & skill. It applies to wood to metal fit as much as the metal work itself and in its highest practice seeks perfection or an absence of flaws from both execution and aesthetic. Machinery has in many cases aided the artist or craftsman, but does not replace him.
Thanks for the op to put my two cents in. Luck in your quest.
