onondaga
posted this
01 February 2014
http://www.castbulletassoc.org/view_user.php?id=6375>John Alexander
We are not going to get a bullet's eye view of the piece of lead origin and formation to a foil piece long enough to wrap around a bullet. It is not like we can install a nano camera on every bullet and watch in ultra slow motion.
We can guess. Something that comes into mind is a disagreement I had with JoeB a while ago. I prefer polishing my bores for cast bullet shooting and have posted my method on this board and recommended it to many. I report that the smooth bore is easier to clean and lead sticks less to a polished bore. JoeB has his disagreement based on literature he cites that I understand him saying a bore that is too shiny attracts lead. I doubt the theory but still will admit the possibility that a certain degree of over-polishing does go beyond what is needed for my polishing method to keep bores easy to maintain.
I don't go finer in abrasive than the Chrome Polish I recommend that has about a 4-500 grit compound. A 1,000 grit would be a lot shinier than I achieve. A lot of shooting past my polishing will burnish the bore finish to a finer finish than 4-500 grit finish.
It could be conceded that a superfine 1,000 grit or a burnished, shot in, superfine finish could allow what you are describing John. Here is a scenario I imagine that creates the thin foils of bullet alloy you describe:
The fine slick bore finish I like does have a bullet alloy repelling characteristic that lessens or stops lead from sticking. I hope you can take that as a given. Lead alone is a lubricious metal and bullet lubricants add to that characteristic. Somewhere and somehow a piece of lead gets ironed flat into a foil between the bore finish and the bullet resulting in the foil you see and note that cleans out easily. It doesn't really stick to the bore tenaciously because of the bore finish being slick and the lead itself being lubricious. I hope you can take that as a given that pieces of lead can be ironed into foil in that way and not be cold welded into a slick bore finish. You want to know where the pieces come from before they are ironed into foil as I understand.
Bearing bands can be sheared by shooting and a piece of sheared off lead will rest in the bore that can be ironed into foil by the next shots pressing the sheared piece between the next bullets being fired and the bore finish. This results in the sheared pieces of lead being flattened and drawn into the lead foil that you note and are curious about their origin.
This is, of course, is theoretical. I have no nano cameras that I can attach to bullets and prove this. There are no witnesses in the bore as bullets are fired.
I also believe mere happenstance will add to this phenomenon and that a bore condition other than a slick shiny bore will also allow the formation of the foil pieces of bullet alloy. Concentricity error in loaded ammo could also start the shearing of particles of bullet alloy that are subsequently ironed into foil.
Gary