If you go to the Mcmaster-Carr catalog you may find expandable brass arbors. I have used them with valve grinding compond that comes premixed with lubricant. You can get it most grits. Depending on the guage select the arbor that is closest to your bore dia. then turn it to a 5 thou under that. you will have to thread a piece of drill rod or round stock to fit the female end of the arbor. Make a stop so that you are not polishing into the choke. lubricate your bore with behr honing oil and you will clean up most bores fairly quickly. With the right grit when you have finished you will have a bore that is smoother and brighter than a baby's bottom after their bath. Less chance with wavey bore dias.
Of course start with 80 or 120 and move to the finer as you go. There is more to this but this is the basics and you should be able to work it out from here.
Be sure to move it back and forth with a smooth even stroke.
Good Luck
John Mc
