Have you checked your loaded round on a concentricity gauge. Could be the ammo and not the chamber.
Tight freebore is a good thing. Shooting it will soon smooth out any tool marks.
from the original post:
"Measured runout, under .001". Just to make sure, I used the hornady concentricity tool to get some rounds dead on 0.000". And tried chambering them. Same deal - scuff on one side."
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