Interesting. Here’s an experiment I did 2 days ago:
I chucked an old Krieger, and polished the sight tenon with scotch brite. This left a decent finish, but there were still some fine scratches around the circumference.
I measured it in various places, and consistently read .7470-.7471” at 76.4°.
I then held a JB patch against it with an estimated 5 lbs of pressure at 725 rpm, for about 20 seconds. I reapplied JB, and repeated this 3 more times. JB turned black, just like it does in actual use.
Cleaned it up with lacquer thinner, and waited for the temp to return to 76.4°.
Fine scratches were still visible. Apparent level of polish or shininess was unchanged. This time, all micrometer readings were .7471”.
I’m comfortable that it is not cutting/abrading 416r.