Barrel break-in - 2 do or not 2 do

[brickcues]

You should follow the manufactures recommendations on cleaning the barrel as all are different. Most of the top barrels makers hand lap their barrels which means the bore has a almost mirror finish. The reason to break in a barrel is the throat which was not hand lapped and still has reamer marks when the chamber was formed and has some sharp edges which need to be polished by firing. When a round is loaded, the throat which is rough, will scrape off fine particles of copper. Upon firing these particles are vaporized and carried and deposited down the bore. Copper sticks very well to itself so if left untouched it will build up quickly and makes the copper fouling harder to remove.

Source:
http://www.krieger.com