re: Opinions on breaking in the barrel on a new deer rifle.

Really depends on the barrel and who makes it. Mass produced, cut-rifled barrels should really be scrubbed with solvent and good bore brush before shooting the first time and a few good cleanings after until the barrel sets in. Mass produced hammer forged barrels probably won't require much more than a few passes with a cotton patch and solvent prior to first time shoiting and less cleaning between firings. High-grade custom barrels will probably be lapped and only require what the maker states. Too many variables to really state a definitive SOP, every barrel is unique in this respect.