ORIGINAL: Briman
I've heard of that happening in 1911's, but in rifles with longer barrels, if its simply gas cutting, why don't we see 'steel' fouling further down the barrel?
Essentially because the tiny fragment of melted steel is pretty much vaporized and exits with the rest of the powder gases. Remember, it is a very miniscule amount with each shot, not like the glob of lead you get from the melted base of a lead bullet!