Bob3700 said:... the bbls don't have to be squeaky clean, they are designed to shoot fouled. With a perfectly clean bore, it will take several shots for the bbl to settle down and shoot well (your rebuilding that layer of fouling).
A shooting buddy & I had a conversation over ice cream a few years back after the day's matches were over at Midwest Palma. He proffered the suggestion that propellant companies actually do a lot of research & development towards making powder residue - what we think of as fouling - actually function as a bullet lube of sorts.
If you look at the ingredients lists of some products you may decide the idea has some merit. That fouling you're working so hard to reduce or eliminate may be better of being left alone....