Dear J-Joe:
You are buying a precision product, an expensive one, and the expectation it will be perfect is reasonable. I'd say being able to see the defect with normal vision is unreasonable as a QA standard for precision machined pieces of steel and assembled in today's modern mfg. world - heck for the last 60-70 years.
R
Revolvers really aren't precision products, the tolerances are pretty wide as far as I am concerned. What this series of videos, they basically install barrels with a monkey wrench, I am frankly surprised they are as well aligned as they are! In the performance center, they are chamfering cylinder holes freehand! Precision? Not hardly!
Naturally the lock works and cylinder gap are hand fitted and really precise where it matters, the rest of the gun is basically finished with an angle grinder and a flap disc

Note my post is a bit tongue in cheek!
Smith & Wesson Performance Center Part 1 - YouTube
Chris