Cydrome Leader fired this volley in
:

just a half inch, or that's as fast as I've bothered with this one
reamer.

Then it sounds like, despite all care, it's not exactly perpendicular to
the hole, or running slightly eccentric; Enough so that one area is
cutting more aggressively than another -- and since they go all the way
around the bore, I'm suspecting eccentric to the shaft.

Where did you get this reamer, and what is: 1) its diameter, and 2) its
cost/provenance.

How are you driving it?

Lloyd