I may be mistaken about this, but I'm pretty sure that S&W stopped pinning the barrels BEFORE CNC machinery was rolled out to the company.
It was done, so I'm told, to make sure that their production techniques would accommodate dropping the pin.
For a number of years, given just how many guns came from the factory with misaligned barrels, I'd have to say that their automated processes took a long time for them to figure out.
We were still seeing more than an inconsequential number of guns with canted barrels up through 1997 or so.
It wasn't uncommon for us to have to send 1 in 20 to 1 in 30 revolvers back to the supplier.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.