Awhile ago I made up a you tube video for a young lad on how to fix a bad crown. It's a quick and easy method and not meant to be the ultimate in re crowning techniques.
http://youtu.be/8PG-VHKfe0Y
In my experience most of the affordable off the shelf barrels can benefit to some degree from a little TLC on the crown.
Please ignore the references to "Jr". It's not meant to be diminutive, that's his forum name.