2) Break-in supposedly works by smoothing the barrel, especially the reamer marks left in the throat. This is accomplished by shooting bullets through a super-clean bore, but the same thing happens if you just clean the bore down to bare steel between range sessions.
MD, I've read what you've written and this makes the most sense to me. Load up the bullet you want to shoot with a few different powders, and see what shoots best. Because you have to do that anyway with a new rifle. It's hard too see what shoots best if you have to stop between each shot to clean; if you clean to bare steel you'd spend all day to get any results. Plus, every shot would be out of a clean bore and those don't always give an accurate picture of the accuracy of a load.
I like to use a good foaming cleaner like Wipeout between sessions to make sure I get all the copper out. Best thing is, it works overnight with no bore scrubbing.
