Chemical Cleaning of Firearms and Accessories: How to Protect Your Investment

By Douglas M. Melton

A hundred and some odd years ago, cleaning your firearm was a pretty simple operation; you used soap and water, and mineral spirits, and then put mineral oil on the steel, then linseed oil on the wood.

Today, we are faced with many different problems with regard to firearms care, particularly with new materials used in firearm construction, special accessories such as silencers, and a much wider range of cleaning chemicals.

This brief overview will provide some guidelines on how to treat difficult situations. We will not discuss normal everyday cleaning of rifle bores with Hoppe’s #9 or other commercial gun care products, but rather the use of non-gun specific chemicals often used to solve difficult cleaning problems.

Metallic materials of construction commonly used in today’s firearms and accessories include ordinary carbon steels, stainless steels, exotic nickel alloys such as Inconel, aluminum alloys, zinc alloys (pot metal), and copper/brass alloys.

Some chemicals that are perfectly acceptable and harmless on one type of alloy can be death to another alloy.

Everybody knows what blued or parkerized steel looks like, or brass, but how do you tell the difference between 6061 aluminum, or cast 356 aluminum, or zinc based pot metal? The simple answer is that you can’t.

Stainless steel is easily identified from aluminum by it’s much heavier weight and hardness, but if you misidentify zinc alloy from aluminum, and use the wrong chemical, you just ruined the piece you were trying to clean. When in doubt, always err on the side of caution.

Carbon steel, including gun steels, will rust if left in their natural state, and are thus protected from uncontrolled oxidation by chemically oxidizing them at the factory to produce a blued or phosphate (parkerized) finish, or to a lesser extent coating them with a paint or baked on finish .

Stainless steels are usually left in their natural state, either polished or bead blasted, but are sometimes black-oxide or coated with baked on coatings. Aluminum alloys are usually either anodized or coated.

Mild steels are always strongly magnetic; they are easy to identify with a magnet. 300 series stainless steels are barely magnetic, and it takes a keen feel to determine any magnetic attraction. 400 series stainless steels are mildly magnetic, and aluminum or zinc alloys have no magnetic tendencies at all. Get a good metallic magnet (not a rubbery refrigerator magnet), and keep it in your cleaning kit. Magnets are your friends.

Nickel based alloys such as Inconel are impervious to anything you can purchase from normal retail outlets.

There are several types of plastics used on firearms. The hard plastics used for some stocks are usually a polystyrene type or derivative, or nylon and its derivatives, or Zytel, or resin reinforced fiberglass, or hard rubber compounds. Some other plastics are obviously used on guns for other parts possibly including ABS, polycarbonates, delrin, and only the gun manufacturers know what else.

It is difficult to identify individual plastics, but it is important to distinguish plastic coated wood stocks from synthetic stocks for proper care.

Some guns or accessories may use a few elastomer (rubber, silicone, viton) parts for o-rings or other seals. These should be watched for so that you don’t dissolve them by using the wrong cleaning compound.

Once you know what materials your firearms is constructed of, you can make appropriate selections of cleaning chemicals for situations that your ordinary gun care products will not handle.

Before we get into chemical choices, I do recommend that you first try the commercially available gun care products such as Hoppe’s, Gunscrub, Outers, and any of the other equally good products first to see if that solves your problem. These companies have invested large sums of money to develop good products, and in most cases they work very well.

However, since you are reading this magazine, you probably have problems that most regular shooters don’t face, such as how to clean the crud out of your silencer, or carbon off your Browning muzzle booster.

Plain old soap and hot water works good on blued steels, particularly to remove corrosive ammo salts, but be sure to thoroughly dry and oil your gun afterwards to prevent a major rust nightmare.

All solvent based cleaners normally found in automotive or commercial degreasers including carburetor and brake cleaner, alcohol’s, acetone’s, ketones, toluols, chlorinated hydrocarbons, et cetera are harmless to carbon steels and their finishes. These chemicals are all degreasers, so you MUST oil your gun after cleaning, or you could end up with a rust problem.

Stay FAR away from caustic, or acid cleaners for ordinary gun steels. Acid will strip bluing or parkerizing right off steel, and caustics can do the same to blued surfaces. Chemicals that are found around the house that contain these are vinegar, lye, as well as EZ-Off and other oven cleaners. Many automotive engine cleaners are caustic, some are hydrocarbon based. Read the label. Anything that says “lye” or “hydroxide” is only recommended for stainless steel or Inconel use.

Most of the above is death to stock finishes or painted surfaces. Use these only on metal parts.

Stainless steel is very corrosion resistant. Only the strongest acids or caustics will cause it any harm. You can clean stainless with almost anything that you can find around the house, or in the garage. Note that many guns are made from 400 series stainless, whereas suppressors usually use 300 series stainless. The 300 series is the most corrosion resistant stainless, so don’t necessarily go and clean the actual firearm with the same stuff you used on the suppressor. You may get surface spotting if you do.

Oven cleaner such as EZ-Off will work wonders to dissolve the carbon build up in STAINLESS STEEL suppressors, or on muzzle boosters. However, if your suppressor has any aluminum parts in it, kiss them good bye, because caustic and aluminum do not go well together. If you use oven cleaner on your muzzle booster, confine it to the inside only, and not on the threads, or outside surface. It won’t hurt the steel, but may degrade the outside finish.

Aluminum is a good candidate for cleaning with water compounds, or non-chlorinated solvents. Read the label carefully on the brake cleaner you bought. If it says “Chloro” something or other on it, do not use it on aluminum. Short duration exposure of aluminum to chlorinated solvents such as Tri-chloroethane, methylene chloride, or similar compounds will not cause problems, but if you combine water, heat, chlorinated hydrocarbons, and aluminum, over periods of time, you can get serious aluminum corrosion.

Brass and copper alloys do not like acid, or caustic chemicals very well, but are usually OK with most hydrocarbon cleaners. They can be a little finicky with some ketone compounds. Best bet for these alloys is mineral spirits and a rag, or fine steel wool.

Zinc alloys do not like any acids at all. Treat them like you would aluminum. Even though aluminum is very resistant to many common acids, don’t take the chance if you don’t know. Use non-chlorinated cleaning solvents or water on these alloys.

Due to the huge number of plastics and polymers used today, there are no hard and fast rules. Some plastics are resistant to everything you can pour on them. Other plastics will melt before your eyes if you use the wrong chemical. Best bet for cleaning is mineral spirits and a soft rag.

Some firearms and accessories use o-rings, or other elastomeric parts as part of their construction. Since different elastomers have different chemical compatabilities than others, I recommend only mineral spirits and gun oil for these parts. Using the wrong cleaning solvent on an elastomer part can cause it to swell and degrade.

The metallic parts of some firearms are finished with a coating of some sort, as opposed to a chemical surface treatment such as blueing, phosphate, or anodize.

These coating generally fall into the wet or dry baked finish categories. Baked powder coated finishes are very chemically resistant to most ordinarily encountered solvents, since they did not use a solvent as a vehicle to apply them to the metal.

A newer type of sprayed finish can be seen with the baked phenolic and baked teflon finishes. Although these finishes use a solvent as a vehicle to enable the applicator to wet spray the finish on, that solvent does not chemically play a part in the finish. It is sort of a poor mans do-it-yourself powder coat. The baking of the dried resins fuses them together to make them very chemical resistant.

That is not to say that you can’t find some concoction that will remove these coating, but rather that normal cleaning with normal cleaning agents or solvents will not hurt these finishes.

A solvent tank that uses approximately 40 parts mineral spirits, 1 part Dexron ATF, and a little bit of lanolin will perform 95% of your cleaning chores, and is relatively safe for use as a cleaning solvent, and is cheap. Remember to always remove the wood or plastic parts before soaking.

But remember, ALWAYS test the chemical on a hidden spot first. Never assume anything is 100% resistant, until you have seen for your self.

Whenever working with ANY chemical, use common sense. Do not work around open flames or other ignition sources. Always have adequate (heavy) ventilation, and wear protective eyewear. It wouldn’t do you any good to have the cleanest suppressor in town if your eyes were burned out with lye so you couldn’t see to shoot it. Some chemicals announce their presence to your nose by their noxious odor, others can sneak up on you, and if inhaled in large quantities, can cause brain, liver, and kidney damage. Some can be absorbed through the skin, so avoid contact. Use disposable rubber gloves. Even though many of the chemicals we use will eat the gloves, they give you some protection from accidental contact.

NEVER mix chemicals! That is a sure way to fire, asphyxiation, poisoning, or death. Combining otherwise harmless chemicals can create poisonous gases such as chlorine, or possible other nerve agents, or cause an unexpected explosion covering you with flaming, or caustic liquids. These can be considered to be “Bad” things.

We have provided a handy reference chart to consult if your cleaning needs are out of the ordinary, and this chart is based on the best data currently available. However, since there are many different guns, alloys used in these gun, plastics, coatings, and the chemicals to clean all these, always proceed with caution. Use the most innocuous chemical first, such as mineral spirits, and then move to stronger methods if the easy ones don’t work, and only use what is necessary, and no more.

Bio: Doug has a Bachelors of science degree in Chemical Engineering from Montana State University, and has been involved in the chemical industry for 20 years, and is also a licensed class 2 manufacturer of specialty firearms, and suppressors. All the information in this article is the opinion of the author.

This article first appeared in Small Arms Review V2N6 (March 1999)
and was posted online on July 15, 2016


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