The late Gale McMillen, maker of the famous McMillen rifles and stocks (now called McBros, and run by his sons), claims that the "shoot one, clean, repeat" barrel break-in proceedure was made up by a barrel maker to ensure that his customers would wear their barrels out faster, generating more business.

Gale built several world-record match rifles, and advises that his were never "broken in"; they were fired at the range and cleaned at the end of the shooting session. He reported that he had seen lots of ruined barrels as a result of over-enthusiastic cleaning, but none from "failure to break in".

I have no cause to doubt Mr. McMillen, and my match rifles were not "broken in" and I still get tiny groups from them.

A minor exception: chromed bores should have at least 200 rounds fired in them before cleaning with a brush (patches are OK), which helps polish the chrome lining. That's the only real break-in requirement.

-Troy