How much rust and the resulting pitting is required before a shotgun is completely ruined for hunting and shooting. I just bought an old shotgun made by Astra that looks like it was shot a good bit, but looked like it had never been cleaned. NEVER!! I don't know what posesses a person to do that. It has small (smaller than my little fingernail)pits scattered on the side-by-side barrel. Inside the barrel it also has small groups of pits scattered in the barrel. I used a Hoppe's solvent in there, then a copperbrush, followed by Kroil to get the crusted dirt out of the barrel. I have repeated that every evening for two weeks. I've done about as much as I can do. So my question is, how much rust and the pits does it take to render a shotgun completely ruined.