OK. I'll Play.
There were NEVER skilled artisans at Colt, Remington, etc., nor at Winchester or any other manufacturer in the 19th century. Those springs were made heavy and "over sprung" cause it was the only way to make em reliable.
The only artisans who tuned flat springs to a thing of beauty have been the few Gunsmiths who taught themselves "spring craft." There are also those home hobbiest(s) with time on their hands where the "cost" is of no concern.
It the cost of making the coil spring, the plunger and the passageway far exceeds the cost of stamping and tempering flat springs. The reason current manufacturers (excepting Colt and now defunct USFA) have gone to coils springs is reliability. Coil springs simply last much longer than flat springs, whether OEM or Tuned.
HOWEVER: I do well understand your preference to be seated at a work bench in a cozy warm place, piddling with your guns as opposed to taking out the trash when it's 24 degrees. You see, yesterday, I spent the entire afternoon in the shop, re-shaping screws and recutting the slots just to make something I personally like better than OEM. It was a toasty 11 degrees yesterday. Making screws beat lots of other options.
Coffinmaker