For the most part, barrel break-in procedures are a waste of time. The first shot will lap out any residual phosphate or other residues that can be found in a new gun and that is pretty much where the effectiveness ends. Each gun has its own tendencies with regards to how much fouling it likes (usually has to do with bore diameter), but you aren't going to correct any rifling issues with a break-in. The throat may clean up a little, but at the expense of throat erosion so it is sort of a win-lose thing. Break-in procedures just get you that much closer to needing a re-barrel, which barrel and gun manufacturers like. That is based on 7 years of ballistic testing, studying, and borescoping barrels as well as observing their performance with the "human factor" removed.
-J