POL is a military acronym for “Petroleum, Oils, and Lubricants.” And “Petroleum” in military lingo generally refers to all types of fuels, but we could rename it for our purposes as “Protectants” or “Preservatives,” which is part of the subject of this article.
The in-depth study of oils and lubricants is rather scientific and in the domain of applied mechanical engineering. The products mentioned in this article are simply ones that I have found “that work” in my 60+ years as a hobby machinist, gunsmith, and shooter. I am simply sharing. I neither endorse these products nor receive compensation from their manufacturers. While the emphasis of this article is on firearms, the information is equally applicable to all tools and garden/farm equipment. I won’t be covering the topic of automobile engine oils. Nor will I cover petroleum fuels.
I prefer to use “specific purpose” products rather than “multipurpose” ones. While there may be many satisfactory multipurpose products on the market, these products in my opinion represent a compromise of some of the desirable qualities at the expense of others, akin to a “one size fits no one” clothing analogy. “Mixing and matching,” (using a product for other than its intended purpose, aka “off label” use) is generally unreliable and could be dangerous. With some notable exceptions, I prefer mineral-based (fatty-acid) products over synthetic, paraffin-based, organic, “water-soluble,” metallic oxides, or ceramic products. Your preferences may vary. “Preservative” products are generally more appropriate for museum conservators, collectors, or as a decoration.
Before we get started, explaining some terms might be helpful:
Viscosity – Is informally described as a fluid’s “thickness,” or its ability to flow or be poured. Much of our knowledge of viscosity has been gained from studies by Sir Isaac Newton. The familiar automobile engine oil viscosity is categorized by its weight, “W.” The higher the number, the more viscous (thicker) it is.
Lubricity – is a product’s ability to reduce friction. Casually, it can be described as “slipperiness.” Lubricity depends on the film-forming and film-maintaining qualities of the lubricant. The value of any lubricant depends on the surface finish and hardness of the material to be lubricated. Temperature, applied pressure, film thickness, and rate of deformation (shear, breakdown) of the liquid all affect lubricity.
In scientific terms, viscosity and lubricity reduce the coefficient of friction, allowing moving parts to move freely past one another.
Protectant – (aka “rust preventatives”) is a substance or agent that protects something from harm or damage. In our case, corrosive rust.
A few words about “Rust” – “rust” is a chemically known as iron oxide. Citing the old adage: “Guns have only two enemies – politicians and rust.” The only way to get rid of first of those enemies is to vote. The other enemy can be effectively stopped by using proper care and a surface protectant.
Rust is the product of a destructive chemical reaction between oxygen and moisture (water) on raw iron or steel surfaces. Not allowing either one of these ingredients to come in contact with an iron surface prevents rust from forming. Simple! Rust can exist as a solid or a vapor. As a vapor, rust can “transfer” from one iron surface to another, without physical contact. Just being close is enough.
Notable exceptions to the negative connotations about oxidation are bluing and browning which are carefully controlled oxidation processes for decoration and protection. They are not within the scope of this article.
Bore “debris” is, in part, the “ash” remaining from the burned priming media and powder. The debris is hygroscopic, meaning it readily absorbs moisture, and, along with the chemicals in the ash, is very corrosive.
Residue from powders that contain sulfur (like black powder), turn into corrosive sulfuric acid with the addition of moisture. Trying to “neutralize” the ash with oils and protectants is totally ineffective. The debris must be thoroughly removed. Bullets propelled down the bore by hot gasses will also leave a deposit was well, and if it allowed to build up, can interfere with accuracy. Modified petroleum products can be used to help remove lead and copper fouling.
Lubricants
Lubricants come in the form of oils and viscous greases. Most home shop uses are for lubricating oils. Greases are designed for heavy stress loads and are considered more or less permanent, making them less desirable for hobbyists and cold weather hunters.
Most commonly used lubricants are oily liquids, but there are some solid lubricants available in the forms of graphite and Molybdenum. Graphite does see some limited gun, shop, and tool uses, but Molybdenum is mostly used in industrial production applications. High pressure-resistant lubricating oils are used in reloading as case resizing lubricants. Common commercially available oil lubricants are 3-in-1™ oil and sewing machine oil as well as specialty branded gun oils.
My preferred lubricant is “Marvel’s Mystery Lubricating Oil™” – NOT their more widely known “Top Cylinder Oil™” engine oil additive! I understand their lubricating oil was developed for use in early air-drive tools to prevent lubricants from “gumming up,” slowing their rotational speed at the low temperatures experienced by those tools, I find it is an excellent firearms lubricant, especially in low temperatures where it does not slow lock times or trigger movement. Its pleasant, slightly sweet smell gradually dissipates over time.
To test your preferred oil at low temperatures, put the container in your freezer overnight and check its viscosity in the morning. The viscosity should be very similar to when it was put in the freezer to be effective in cold weather shooting conditions.
Before applying lubricants, the surfaces should be cleaned to remove the “old” oils and abrasive particles. Pin-point re-application is easily accomplished with a 5 or 10cc Luer lock syringe and an 18 ga blunt “needle” (or cannelure). (See your dentist for one.) Marvel’s™ oil does not degrade the plunger’s gasket in the short term.
Automobile engine oil is not suitable for lubricating anything other than automobile engines! These oils are designed to work at high temperatures and could contain ingredients capable of staining or damaging metal surfaces. Common “off-label” uses include muzzleloading gunsmiths’ widespread use as a quenching media, especially for flat springs. Techniques for use its can be found in the muzzle loading literature or online.
Mineral Oil, USP is a highly purified mineral oil for pharmacological use. It is also an inexpensive lubricating or quenching oil. I estimate it to be about 10WT. Lard, an organic oil, was often used as a lubricant in period guns, as is raw linseed oil. Sperm (Whale) Oil, also an organic oil, was once preferred as a lamp oil and lubricant by early gun makers. It now has severely limited availability due to strict whaling prohibitions. It was the preferred lubricant of watchmakers and precision scientific instrument makers. It is practically unavailable but, if it can be found, it is too expensive for today’s sporting arms.
On the rare occasions where Grease is needed, my go-to is Lubriplate™ products. Invented in 1870 by Robert L. Watts, and marketed by Fiske Brothers Refining, Toledo, OH, they have a wide array of products for lubrication and corrosion resistance for many applications, including firearms. And, they market small quantities suitable for small shop use.
Protectants
As their name implies, these products protect iron surfaces from rust. They are usually chemically modified hydrocarbon oils, greases, or silicones. All rust must be removed before applying a protectant or else the rust could continue under the protectant.
Cosmoline is an often-heard rust protectant used on firearms. It originally was a trade-named greasy substance invented in the 1860s for the medicinal, veterinary, and cosmetic trades. It was later found to be an effective rust protectant on farm equipment and later applied to guns. Many military surplus arms for civilian sale are generously preserved in it. (Analogous to: “If I little is good, then a lot has got to be much better.”) Its use was so commonplace in the military, it even has given its own Mil-Spec number. It is a flammable, smelly, brown, greasy substance that hardens over time, making its removal difficult.
RIG™ (Rust Inhibiting Grease) is my preferred protectant. Even a thin film works effectively to protect against rust in even the harshest environments. Originally developed by RIG Products, Sparks, Nevada, it is currently marketed by Birchwood-Casey™ and is widely available. The active ingredient is petroleum sulfonate and it is practically odorless. It will separate over time, but a quick stir mixes back into its original consistency and effectiveness. I find it especially useful on firearms placed in long-term storage as it doesn’t harden over time. I still have less than ¼ of a 15 oz-can remaining that was purchased 25+ years ago.
A 6” x 6” piece of durable soft cloth lightly saturated with RIG™ and stored in a Kiwi Shoe polish can to protect it from dust and abrasives, is my “RIG™ Rag,” ready for instant use. If the rag is accidentally dropped on the floor is easily disposed of and quickly replaced.
Petroleum-based and natural waxes can also serve as effective protectants. Their thorough removal might be problematic.
Cutting Tool Lubricants
These specialty products possess high shear strengths because of the intimate contact (friction) between the tool and workpiece. They receive almost exclusive use in machining applications, such as threading, turning (profiling), and cut-off operations. Cutting oils can also contain extreme pressure additives and fatty oil ingredients to reduce cutting friction. Cutting oils can produce a smooth finished surface. They can be applied in quantity by a brush, a drip, stream or spray. When applied in a stream or spray, they can act as coolants as well. Gunsmiths and machinists use cutting oils for tapping internal screw threads and/or cutting external threads with a die. Oils should never be used on files.
The addition of sulfur to an oil enhances its cutting properties, and its presence is readily detected by the smell. Odorless sulfurized cutting oils are available, as well. The addition of sulfur allows the cutting oil to form an effective, high-lubricity boundary layer between the workpiece and cutting tool to reduce friction and heat and contributing to a smooth surface finish. They are dark, metalworking fluids that are recommended for use on ferrous metals and certain other non-ferrous metals, such as nickel and certain types of aluminum and aluminum alloys. Their most common use in gunwork is for custom barrel profile turning, tapping, threading the barrel breech, and threading breech plugs on muzzleloaders.
For hand threading applications using small taps and dies, my preference is Tap Magic™. For larger hand threading jobs and machine applications, my preference is Rigid™ Extreme Performance Thread Cutting Oil. It is difficult to obtain quantities of machine-cutting oils small enough for the hobbyist gunsmith.
Machine Maintenance Oils
If you are fortunate enough to own expensive metalworking machines you probably feel the deep-seated need to maintain them in tip-top condition to protect your investment and produce accurate results. This means performing regular routine maintenance. Machines should come with owner’s manuals that instruct the operator on proper procedures, and the appropriate lubricants.
“Oil is cheap; bearings are not.
Run your machine dry, and you’ll regret it a lot.” (Thanks to Ilion for the poem)
Follow the instructions carefully for the lubrication points and frequencies. One of the better spindle oils is Mobil Velocite™ 10 (ISO 22). A good gearbox and drive train oil is Mobil DTE™ (ISO 32). It is also a good general purpose maintenance lubricating oil, as well. Ways (slides) should be lubricated with a high sheer-stress oil such as Mobile Vectra Medium Way™ oil. Obtaining these products in small enough quantities for the hobbyist can be challenging.
Keep your metal working machinery covered with a heavy, close-weave cloth or canvas to protect it from dust and abrasive particles. Washing the cover occasionally is a good practice as it removes accumulated oils and dust. Plastic sheet is not recommended as a cover because it traps and holds that demon – moisture – arising from cement floors.
Specialty Products are intended for special, specific, limited-use purposes. Some of them are:
Electric motor oils – especially designed to effectively lubricate the load on electric motor bearings at their rotational speeds, and for its non-conductive properties.
Quenching Media – often referred to as “Tempering Oil,” is used in heat-treating steel to quickly reduce the hot metal’s temperature (quench) to bring about atomic structural changes in the steel. Oils, water, and air are examples of quenching media. To be most effective, the steel’s composition should be matched with the quenching media. Specially designed quenching oils (available from Brownell’s) are preferred over auto engine oils for best results for the reasons listed above.
Honing Oils – are used in edge tool hand sharpening. They are designed with a dual purpose – to provide edge lubrication and to keep the abraded metal particles in suspension to prevent them from “clogging” (loading) the abrasive stone, reducing its cutting efficiency. They have a low viscosity, to accomplish these two objectives.
Water – while not a petroleum product, it is used as a lubricant to prevent clogging of soft abrasive polishing stones. Its method of action is similar to honing oils.
High temperature grease – is often used on the threads of muzzleloading breach pins (plugs) for lubrication to aid in its correct alignment with the barrel flats and to form a water-proof seal that prevents the water used in cleaning from entering the threads, and rusting the pin in place. These greases often have lithium as their primary additive. Its high-temperature resistance protects it from breaking down under shooting conditions.
Bore cleaners
Hopes #9™ – the old standby cleaner/lubricant for cleaning centerfire gun bores. There are new products on the market designed for specific purposes but I question if they are truly any more effective for the average shooter. Your mileage may vary.
After swabbing until a clean patch is achieved, the bore should be wiped with a dry patch followed by a lightly oiled one. Excessive use of hydrocarbon oils in the bore is discouraged because of the potential for ash-residue build-up when the gun is fired. Therefore, a dry patch should be used to remove as much oil as possible before shooting. The chamber should receive special attention. An oily chamber will not permit the expanding brass case to “grip” the chamber walls and reduce rearward thrust (“back thrust”) on the breech face and locking lugs.
Black powder – A strong solution of Dawn™ dish soap and hot water has proven itself as a most effective black powder bore cleaner in my hands. After cleaning, the bore should be carefully wiped dry, allowed additional drying time (perhaps augmented with low heat), followed by a lightly oiled patch or swab when thoroughly dry. Cleaning black powder substitutes is managed the same way.
Ed’s Red is an effective homemade centerfire bore cleaner. But it is impractical to make in small quantities for the hobbyist shooter. Perhaps, a club could use it as a revenue source.
Rust Removal
Surface rust can be light and flakey, or pitted to varying depths. Light spotty surface rust can be removed with a light rubbing with OOOO or OOOOO stainless steel wool and Hoppe’s #9™. A soft wire wheel will remove some shallow rust pitting that was not removed by the steel wool. Be careful not to damage the surrounding finish. Deeper pits? – well, you have to either accept them as they are, or a complete refinishing job is in your future.
Bead blasting is the most effective rust removal process, but in small shops, a gentle wire brushing is more practical and cost-effective.
Oil and Protectant Removal
All oils and greases will hold abrasive particles; they need to be replaced often to reduce wear. Safe removal is problematic. For most moving parts, a thorough wiping is usually satisfactory, unless there are copious residual dust and abrasive particles. Re-lubricate as described above.
All oils, including fingerprint oil, must be removed prior to bluing or browning. For bluing and browning, boiling (!) water and a strong solution of Dawn™, Spic n Span™, or other low-residue detergent is effective for oil removal.
Many volatile solvents have been used to remove Cosmoline, but inhalation of their fumes is very toxic. If used at all, they should be used outdoors or in a well-ventilated environment. There are many YouTube videos showing how to remove Cosmoline.
Resources:
- Oberg E, Jones FD, Horton HD, Ryffel HH, Machinery’s Handbook, New York, Industrial Press, 2004
- Rapp P Engineer’s Black Book, USA ed., Perth Aust, Rapp Enterprizes, 2005
- Ilion Industrial Services, Basic Maintenance for the Vintage South Bend Lathe, Raleigh NC, 2020