I guess that means that cleaning your rifle with a wire brush, as most gun 
owners do, would change the ballistic fingerprinting. Doesn't really appear 
to be a viable solution to the problem.
I know from my military experience that regular cleaning with a wire brush 
was required to remove powder deposits and any other corrosive materials that 
might get into your barrel. I suppose any dirt would also mar the surface and 
change the fingerprinting.

Rummy..........I'm always amazed when people, who know very well what they 
are doing, post items to this list that really light people's fuses. We go 
through this time after time and yet, we never learn what's really important.