I guess there is some point of rarity where the decision would be not to bore, but the whole originality thing I never bought on this common question. Which is more desireable, original barrels with pits, discoloration, fouling and marks, or a useable gun with smooth safe barrels that are easy to clean, shoot better and look presentable but have been bored or honed out a few thousanths of an inch in diameter? I know what my answer would be and what I have observed on the impact to market price on several hundred auctions I have tracked over the last several years. If it will be safe, I will clean them up every time unless the gun is so low valued you can't justify the investment. In that case you should the gun as is and put up with the cleaning.