Re: Barrel break in
My experience with factory vs premium aftermarket barrels tell about opposite things. Regarding premium aftermarket, the above reflects just about the same as I found with my L-W replacement barrel. After a few shots, it usually stops fouling aggressively. I clean for the first few, to determine when that fouling rate shifts to negligible, but that's just 'cause I'm a control freak.
Factory barrels are seldom produced to the same interior finish standards, and the fouling reflects this. But I am not at all convinced that aggressive cleaning during initial shooting has any meaningful effect on how soon the aggressive fouling will abate.
IMHO, the only significantly beneficial wear-in occurs as the machining marks from the throating operation are abraded/ablated down. This occurs as a normal part of the natural shooting process.
I give a rifle about 100 shots to settle down the throat before I begin serious load development. Those first hundred shots are most useful for the pressure testing and fireforming processes.
Greg