There is no doubt that today's modern manufacturing methods (especially CNC machining, modern metallurgical marvels, and tooling that was just an impossible dream seventy five years ago) has made the improvements in current firearms that would seem a pipe-dream to the gunsmiths of that earlier era.
BUT - - - the craftsmanship and pride of the work that went into those earlier pieces is so thoroughly lacking in the modern lines of guns and makes some of today's stuff seem like it was produced by blind idiots underwater in a high-volume outhouse.
If you want the pride and craftsmanship of yesteryear's guns, you must pay double for it and it is labeled as "Precision Marksmanship Unit" or somesuch prideful banners, and yet many of those still need tweaking or sometimes major adjustments even after they pass at such a price.
Mass-production is intended to lower the price per unit while producing more serviceable units. Usually it works for the economy of scale is a rule that is hard to break. "Serviceable" is the key word here.