While we know that corrosive priming certainly led to much barrel pitting, it was not/is not the only cause of it in shotguns. Before plastic shot cups came along there was precious little protection from lead scrubbing the bore. This, in time and when not cleaned properly, caused leading of the bore ...... places where a very thin piece of lead sheet was attached to the bore, built up from hundreds of times that the lead shot scrubbed along the bore wall. When this was not cleaned out thoroughly, moisture migrated underneath it, and rust began. Thus, pitting. Corrosive primers, of course, exacerbated this condition.
Not much of a problem these days, with shot cups containing the load.
SRH
Last edited by Stan; 09/04/16 05:25 PM.
