Rust is the enemy of all metal objects, and collector and antique firearms. Nothing aside from fire can destroy the value and appearance of a vintage firearm faster than rust. Any metal product, no matter what kind of protective coating it has, can develop rust in the proper conditions. This even includes modern guns like GLOCKs. Yes, even GLOCK pistols can and do develop rust if exposed to specific conditions.
Let’s start with the most basic question: what is rust? Rust is an oxidation of iron oxide formed by the reaction of iron and oxygen in the presence of water vapor or moisture in the air, or on the surface of the metal. It breaks down and converts the metal of the item to iron oxide. Rust can take many forms from little tiny spots on the finish that look like frost on a window, all the way up to big gouges in the metal that look like lesions on the skin. Any material composed of iron (in whole or in part) is susceptible to rust. So, this would include every firearm out there.
You can slow down, or in some cases almost prevent, rust with the proper coating of protective oil or paint. Just take a walk around any Civil War battlefield and look at all the cannons; they are coated in paint so thick you can't read the maker's marks anymore. Oil is also very effective in protecting exposed metal from rust. However, it is very impractical to heavily coat firearms in this. You end up either making a mess, or having a super slick gun you can’t grab. Also, it is nearly impossible to keep this protective coating in place long-term, especially on firearms that are in daily use. Rust is an enemy that all gun owners fight.
Now that we know what rust is, what can we do to prevent it and what do we do once the rust is already on our guns? The short answer is that you need to find some methodology to stop the rust from continuing, and then remove the existing rust.
The best method to prevent the growth of firearms rust is proper application of protective oil and removal of moisture from the air. Whether you use some form of desiccant or a dehumidifier, it is essential to keep your firearms as dry as possible. Additionally, especially when storing firearms for a long time, you want to keep your guns as well-oiled as possible. You want to leave a good coating on all exposed metal surfaces to prevent the adherence of moisture.
When rust does get on the gun, it can go from minor spotting on the finish to deep pitting very quickly. So, you want to remove any rust as soon as it is noticed. There are a few methods which have been tried and tested over the years to remove rust from a gun most effectively.
You are welcome to try all the “wonder solutions” out there on the market, but the best methodology we have found is more old fashioned. It involves using extra fine or so-called 4 ought steel wool and oil of some sort, usually just plain gun oil. At this point you're probably going to be thinking “wait a minute won't the steel wool scrape the finish off?” The answer is no, as ‘0000’ steel wool is too fine and soft. Rust tends to be softer than blued metal. So, it can be easily removed with a little elbow grease.
Cover the entire surface you're going to be working on in a good coat of oil, and then use the steel wool on any rust spots rubbing over them. You can use either circular or lengthwise strokes - it doesn't really matter as long as you’re consistent. The goal is to use the steel wool to catch the edges of the rust and peel it off the underlying metal. Feel free to apply pressure too — you're not going to hurt the underlying metal. In most cases it won't damage the bluing. You may see minor spots where your strokes are visible, but realistically it is better than the rust which was on the surface damage wise. If you are concerned that it will damage your finish, you can always use brass wool. Brass is far softer than any type of gun metal and thus won’t damage it.
While removing rust from a gun, you are going to run into two issues almost inevitably. The first one is pitting. Unfortunately, there is nothing you can really do about pitting without refinishing the gun entirely. Any rust which has gone through the finish and begun to eat the base metal is beyond basic repair status. For that type of repair, you may need to take it to a gunsmith.
The other issue you may run into is hard spots. These are usually rust spots which have gotten more moisture trapped and have started to bubble up through the surface and cause more lasting damage. These can be removed using either a small piece of brass or a pre-1970s U.S. nickel coin. These are made of a softer metal and can be slid along the surface without hurting the finish in most cases. You want to rotate the coin every now and then to get a fresh edge against the rust you are trying to remove. Essentially, the nickel or piece of brass acts like scraper to remove the harder bits.
No matter which method or tool you use to remove rust from your gun, there are certain things you must do. Throughout the rust removal process, you want to stop occasionally and use a rag to remove the oil and any loose rust. This is so that you are not simply spreading it out, and so it does not fill in the rust bubble and make it so the steel wool cannot catch it anymore. It also allows you to see the effect you are having, and how much of the rust you have gotten off.
Most importantly, when you are done removing the rust, make sure to double check that you have recoated the cleaned off surface with a fresh coating of protective oil. Anywhere that you have removed rust will be bare metal that is now exposed to the elements. This needs to be protected. You may need to investigate having your firearm reblued or refinished depending on the level of damage on its finish.
Sometimes the level of damage is too severe, and you may need to investigate replacing parts to make the firearm safe to shoot again. If you are a gun collector, you obviously want to keep your firearm as original as possible, but safety may demand otherwise. If after you follow the above steps you find that you do need some replacement parts, we have a massive inventory of gun parts and are happy to help. In the meantime, good luck removing that pesky rust!