TinMan88- Rust is caused by loss of electrons in the steel to an outside agent that will accept electrons. Water has some H+ ions in it and they will grab the negative electrons. Many other substances have + ions and they will also cause rust. The only way to prevent rust is to keep the gun away from anything that will accept the electrons from the steel or keep a protective barrier (oil) that prevents the + ions from contacting the steel.
storing guns in a closed case of any kind will come back to bite you. They need to breath. I learned my lesson once. This is especially true in humid climates like the midwest. Out here in the west it does not seem to be an issue
<blockquote><i>"which scotch bright is the least abrasive, and where do you buy it?"</i></blockquote><I>McMaster-Carr sells Scotch-Brite #7448</i> or the equivalent grade in the generic pads. Always use with some sort of lubrication (oil, mineral spirits, etc.)
I've pulled this page out of the web site directory. It has lost some of it's links to the rest of the site so "Back" doesn't work. Pull the web site up using the home link and navigate to the product on your own if you want to buy it. You can also call them. They are terrific folks to work with no matter what size your order.
Use a bronze brush chucked in a hand drill and have at it with a few drops of oil. Some might cringe at using fine steel wool wrapped around the bronze brush with oil but give that a try if scotch brite does not work for you.
Tinman88 - the product you are talking about is ospho sold by Sherwin Williams and others. It is a phosphoric acid solution that is said to neutralize rust. We use it and it works great. Yes, it does turn any rust on the metal black. Ospho will neutralize rust but it will not stop the item from rusting in the future. Ospho is not a primer or paint. You must provide other protection after using it. I have not tried this solution on blued metal or finished wood and do not know how it would react but the work acid makes me not wanting to find out.
Something that I have used on chambers and Briley choke tubes for a few years now is a Remington product called 40-X bore cleaner. Haven't seen a down side to it. I shoot my rifles so little that I haven't used it on them. Instructions are on the bottle, it is available in my town at Wall Mart. Regards, John Hancock
Remember this...each time you see rust, there will be a pit, AND each time you remove the rust, you have just removed a small portion of metal.
The best option the first time you see the rust is to remove it by any of the suggestions above, then always after each shooting and as soon as possible, oil the bore and chamber.
Do not under any circumstances begin an attempt to polish the chamber with any type of grit paper of cloth. The chamber will become oversize leading to a sticky empty hull situation. Also, polishing the chamber could lead to a problem if you do eventually need to have a sleeve installed. The sleeves are cut to SAAMI specs, and it could be possible to have a step deeper into the chamber where the oversized bore is larger than the newly cut sleeve.
About the maximum for an oversized chamber is .820", measured just below the rim cut.