The main concern is deep pits and removing all the rust. Rust is a cancer on steal and continues to grow if it is not removed completely. Some collectors guns are left pretty much alone and the patina as it is called should be left undisturbed. Such old guns should have the local gun smith make the decision as to what should and should not be done to preserve the guns value.
The purpose of this article is to take a gun with little value and turn it into something that will shoot. This gun was a neglected WWII Japanese 7.7 Arisaka. This gun was in a wet climate for 7 years without re-oiling or proper maintenance. The owner previously had it for a few years in a desert climate, before he moved it was oiled one or two times and it had no problems with rust.
To do this type of work you do not need a lot of fancy equipment or solvents though they can help. A product like PB, Nut Buster, Penetrating oil, etc. is excellent for stuck parts and screws. A rusty screw can twist off which would be a disaster and expensive to fix if that occurred and perhaps more cost to repair then the gun is worth. Things that will not come apart should be sprayed with PB about twice a week and the gun left to set for a couple of weeks while the oil penetrates. A revolver should never be taken completely apart the most that should be done is to remove the side plate and this only if the gun is nonfunctional and clean and oil the gun. Most military rifles can come apart mostly by hand action alone and some screws may need to be removed depending on the gun.
First this Arisaka was completely disassembled and rubbed with oil and an old brass shell casing then scrubbed with a brass brush and fresh gun oil-- no solvent was needed to take the gun apart-- no parts were stuck. A brass shell casing should be used vigorously, it is softer than the steel and will leave the remaining bluing and remove the rust. Never use a grinding wheel or electric power tool with a spinning wire brush.
Yes this is the same gun in both pictures
The cleaning time depends on how much rust is on your gun. This particular gun took me about 3 hours to clean. If you have a gun that you don't have time to take care of, rub it down with a thin layer of bearing grease before you store it. This will help to protect your it from rust in the future.
Let me know how your rust removal project went in the comments below!
Richard W Norman