Powder, patches, balls, percussion caps,and range time.

Actually, for a new barrel I like to give it afew (4 or 5) passes with a well oiled patch wrapped with #000 steel wool, thenshoot a box of Great Plains conicals and fully clean and oil the bore between each of thosefirst twenty rounds. It's a pain, but I believe (can't prove it) those long conicals hone the bore a little and it willfoul less with such a break in.