The reamer is nice DROX, but not at all necessary.

I use a ball that's larger than the bore (a large marble, lead ball for the next caliber up, a wood furniture knob, etc.) and progressive grits of emory paper. Cut the paper into inch-and-a-half squares and use the ball to rotate it against the bore. You have to change the paper fairly often. Start with something like 150 or 200 grit and move progressively to finer grits. I usually finish up with 600 grit with a little oil or water on it. You'll be done in about fifteen minutes.

The thin angle iron used for bed frames works well as a guide because it's very hard stuff, (heat treated or something).