Matweb.com is a good resource for information on materials and their composition.
Stainless steel gets its corrosion resistance primarily from chromium, which it has in the range of about 11% to 30% by weight, depending on the alloy, so it is much more than a trace quantity. Like aluminum, chromium forms an oxide layer upon contact with air, and it is this chromium oxide protects the iron in the steel from corrosion. The austenitic stainless steels, like 302 and 316, also have about 10%-20% nickel and are the most corrosion-resistant types and are often used for medical instruments because they tolerate harsh sterilizing regimens. However, they are not heat-treatable for hardness but can only be hardened by cold working, limiting their range of application. Gun stainless steels are usually something like 416, which is about 13% chromium. It also has up to about 0.15% carbon, which helps with its hardness, but interferes with corrosion resistance, which is why a "stainless" gun can still pick up rust spots (the other is that it was shaped with steel tools that left some free iron behind on the surface which can be rusted; that free iron is what "passivating" in nitric or citric acid eliminates by etching it out).
Longshot4,
A number of the top shooters historically have had their own formulas for cheaper cleaning products they like. But my general experience has been they all have drawbacks or are inferior to some of the specially developed stuff. For example, you will find the additives in Mobil 1 synthetic motor oil do a pretty good job of removing carbon just as they do in an engine, and the cost per quart is low compared to gun cleaners. But is it as good at softening hard carbon
Carbon Killer? No. As a bore cleaner, does it attack and remove copper fouling like
Bore Tech Eliminator? Not at all. Does going to ammonia solution make up for it? No. It's slower and activates and rusts non-stainless steels if you leave it too long.
You can probably save some money grabbing copper with CLR and its surfactants may get some carbon and its lubricant may help prevent corrosion after it micro-etches the surface of a non-stainless bore, but it's still doing something it wasn't designed for and therefore caution is indicated to ferret out any issues it may have rather carefully. In the process, you can compare it to the other products I mentioned and see if the cost saving is worth the extra time you need to get done? The thing I like about Eliminator, in particular, is I can put some in the bore at the range at the end of a session (I use a small pump sprayer) and plug then ends and go home. I then run a wet patch through it followed by a dry patch five minutes later, and generally that's all that's needed. No brushes or abrasives or anything else. The gun's ready for the next range session.
This article is old but good information.