Scott: First off, a set of barrels doesn't necessarily have to "ring" to be good. You have to know what to listen for. A "buzz" or a dead sound is not good, however. It bears investigation. if they've been cut, all the more so. While you can personally look for a loose rib, the professional needs to assess the situation. This is usually the same fellow who can re-lay a loose rib. Sadly, there are just a handful of these people in the country.
If in doubt, send the barrels to Kirk Merrington:
http://www.merringtongun.com
I'm sure you will get a score of other strong opinions on this. But all will be just that. Trust a pro.