The barrel should be fine unless he has shot several thousand rounds. I would say in excess of 5-8 thousand unless he just kept shooting with a very hot barrel. There have been reports of barrels shooting 10-30 thousand rounds with virtually no loss of accuracy in a 308.
Double check the crown first, check the ignition and possibly put a new spring in it. Check scope and mounting again. Do a deep clean with copper solvent that sits in the barrel, and clean until all traces of copper are gone. This may take a couple of days.
Cut to the chase: bore brush, patches, JB compound.
