Hopefully before you fire your gun you clean it carefully and remove all the gunk left from the factory proof test and any bits of packaging that may be in the bore. I think breaking in a boret is a good thing and hasn't hurt any of my guns and in fact makes them clean easier but you have to be thorough. First 10 shots run patches down the bore every shot until they come out clean. The next 10 every 2 shots and then the next 30 shots every 3 shots. That will remove most of the copper buildup and smooth out the bore and polish some tooling marks. You can use any good bore solvent and or copper cleaner or both, just follow directions. FWIW