@Nav Thanks for a well thought out and detailed post.
But, we still don't agree. I think that some of your information regarding modern precision barrels is positively informative but not so much on point with ml barrels.
There are very few makers of precision ml barrels whose work comes anywhere near the quality of work being done by the modern precision makers. Further, the advent of non corrosive primers has made a huge difference in the longevity of modern barrels. Even those that are treated with what would have previously been considered gross neglect.
Not so with our ml guns. We continue in the use of our highly corrosive propellant, including modern subs. The traditional use of the patched ball has, when the patch is properly fitted, been the protection against lead deposits. But, the use of conical lead bullets has made lead deposits in our relatively rough ml barrels pretty much much a certainty.
Then when the failure to remove the lead is combined with the lead covering the BP fouling the result is fouling traps between the lead and the barrel steel. The result is corrosion and pitting.
I found your concept of the improvement of modern barrels by the smoothing action of copper deposits to be very interesting but given the above I don't consider it a viable strategy for conditioning an ml barrel.
I have seen personally the results of fouling trapped under lead in an ml barrel so that's why I'm adamant about the necessity of removing it. Also why I rarely shoot conicals in my ml guns anymore and prefer the patched ball to having to deal with actual or even possible lead deposits.
My method of removal is steel wool and I see no evidence of it doing any damage to the bore. But for those who are reluctant to use it then I say all well and good but at least use some reliable method of getting the lead out.
As long as we are letting modern stuff into the topic, every shooter of lead bullets in cartridge guns knows that lead deposits are inevitable and that they cause declining accuracy. So it's probably true in a ml gun as well.