If you buy the hone from a gunsmithing supply house, you'll pay $30 to $40 each but if you get it from an automotive supply house, you'll get it for $10 to $20 each. Search for "Flex Hone". I've gotten them from these guys but even they're kind of expensive. This particular one is a .315 inch 320 grit but they have all sizes.
http://www.grainger.com/Grainger/items/2ZYK1?Pid=search
They're listed in decimal sizes so you'll have to convert the case diameter to thousands of an inch. Try this site for all types of measurment conversions.
http://www.towerhobbies.com/help/convcalcs.html
The hone has to be slightly larger than the chamber size. A couple of things to remember when honing:
**Start the end of the Flex Hone into the chamber about 1/2 inch before starting the drill. If you start spinning it before it's inserted, it'll bend over and smack you! (Been there and done that!!!)
**Be carefull not to pull the hone out of the chamber when it's spinning. (See above. Trust me. You'll only do it once because it HURTS!!)
**Keep the hone moving back and forth.
** Keep the lube flowing over it and into the end of the chamber. I use flowing water in the sink and spin it with an air drill. No electric drills in the sink!
** When you're done, turn off the drill as the hone is being withdrawn from the chamber. The idea is for the hone to not be drug straight out or it'll leave scratches inside the chamber. The trick is to have the hone stop spinning just as it leaves the chamber. If it's going to fast, it'll bend over and then it feels like somebody just whipped a car antenna across your fingers. (Yeah, I had that happen too!!)
**Use a little bit of caution with a ball hone. The flex shaft should be kept straight. It can be straightened if it get's bent. Watch loose clothing around the hone end. It will snag loose clothing and wrap it up tight. That's not fun to experience but really funny to see somebody with a drill hanging from their wadded up shirt! heh heh. Keep yer powder dry, Mac.
Tuff-Gun Finishes. The Name Says It All.
Mac's Shootin' Irons
http://www.shootiniron.com