Light lead traces form just beyond the throat almost immediately, then just stop growing. They seem to be shooting themselves clear as fast as they accumulate thereafter.
Ah, thanks Unclenick, you have no idea how happy this makes me. I noticed these same traces in my (relatively new) SR1911 and wasnt sure if this was normal or something to be concerned about.
Rather than concern myself with getting every last speck out of the bore in this area I guess I will continue cleaning as I normally do and monitor the areas for growth. I had just assumed that if there was anything there now it would just get worse with time.