I bought a chucking reamer in .452 diam from MSC or McMaster-Carr for something like
$15 new. Ream a piece of steel scrap FIRST to clean off the burrs a bit, then mount the
cylinder in a v-block in a mill vise, and let the vise free float on a mill table so the holes
can self align. Then feed the well oiled reamer at moderate speed with the quill and
let the cylinder self align laterally, it is held vertically by the v-block and mill vise. I oiled
the mill table to let if float smoothly. Reamed OK but a touch rough looking, I polished with split
dowel to .453. Did both cylinders on a convertible BH, worked well for cheap.
There is an old thread on this in the gunsmithing section of the other site, with pix.
Use the same setup with a brass lap and you will have total control of the process,
diameter and surface finish. Brass laps are about $20. Slower but safer and will be
very cylindrical, too.
Bill