typically done by using a compound on a patch and running it through the bore multiple times....sometimes different "grit" compound is used etc....
the compound is somewhat abrasive and polishes the bore...
i think im going to have my new rifle done...especially after running patches through it today and seeing the metal filing i got out with just patches!
it should also shorten the break in period of a new rifle and help the bore "settle down" quicker...
only reason i'm taking mine to get done is because the smith gotta do a bit of work for me...going to have him mount the scope, put sling studs on, and see if he cant do much with the trigger...and lap the barrel for me...