Rust Preventatives for Firearms

I am an anti-corrosion fanatic and a lubricant nut, ever in search of the best product to prevent rust and keep moving parts moving, whether on guns, on vehicles, or around the house and workshop. Maybe that’s because when I make an investment in a firearm, a hand tool, a car, or whatever, I want it to last.

Over the years I have accumulated numerous products that claim to lubricate and prevent rust. Some are dedicated gun-care products, and others are household and automotive products.

So far, I have rarely been disappointed by one of these products so far as gun maintenance is concerned. But then again I will have to admit to being somewhat scrupulous about cleaning, lubing, and wiping down my guns with good a preservative to prevent rust.

Recently I was inspired by a home test performed by a fellow member of the Curio & Relic FFL E-mail list. This industrious chap tested a few products he had on hand to see how they prevented rust, and reported back to the list over the course of a week or so.

As fine a job as he did, he really didn’t have too many products on hand to satisfy my own curious nature. After all, if all of the products I have used weren’t tested, I wasn’t happy.

Thanks to all of the recent rain we had where I live, I found myself one summer weekend running my own tests. My goal was simply to see what products, when applied as I use them on firearms, would stave off rust the longest.

Test 1: Single Dose Exposure

The first round of tests was designed to test the effectiveness of a relatively heavy coat of preservative with a single, heavy dose of salt spray. I figured this gave the products a fair chance to see if they could ward off moisture as might be encountered on a wet hunting trip or during a day where one’s concealed carry handgun rides against a sweaty body.

The first test used 1½ inch bright finish nails, thoroughly cleaned with steel wool to remove surface oxidation until they were all shiny. All of the nails were then degreased with Kleen Bore Gunk Out spray, wiped with clean paper toweling while still wet, and then spray degreased again and patted dry with clean paper towels.

Thereafter, the nails were handled only with forceps that were cleaned and degreased. The test products were applied directly to the nails from the bottles or cans. If the product was a liquid, it was dripped from the top of the nail down to the bottom, making sure all sides were coated. Products in spray form were applied by spraying the nail as it was rotated, to ensure full coverage.

Whether spray or liquid, I purposely used more than enough of each product to ensure full coverage. Between applications, the forceps were degreased to prevent cross-contamination with other products while handling the nails.

After each nail was coated, the excess product was blotted off with a piece of clean paper towel. The object was to keep the nail wet, but not dripping, with the test product. Two polished, degreased nails remained uncoated with any product to serve as controls.

The products initially tested were:

bullet Kleen Bore TW25-B bullet Break Free CLP
bullet Break Free LP bullet Shooter’s Choice Rust Prevent
bullet Birchwood-Casey Sheath bullet Remington RemOil
bullet Eezox bullet WD-40
bullet Kano Kroil bullet 3-in-One Household Oil
bullet Sandaro Industries’ Bore Cote bullet Miltec-1.
bullet Sandaro Industries’ Arms Cote

Each of the nails was placed on a sheet of wax paper that had been divided into a numbered grid with magic marker. Each nail had its own section of paper where it was not in contact with any other nail.

A saturated salt solution was then prepared in a clean spray bottle. In this case, Diamond Crystal Kosher salt (which is not iodized) was added to the water in the bottle until salt crystals started to precipitate out of the solution. A little more water was added to dissolve the precipitated salt, which got me pretty close to a saturated solution. I figure this was about as severe a test solution as I could concoct.

All of the nails were sprayed down until a small puddle formed around each one. Ambient temperature was a mostly constant 75°F, and relative humidity was around 65%.

The salt-sprayed test nails were allowed to air dry, and the results were observed periodically. After 22 hours, the test was stopped because the uncoated control nails had almost completely rusted, and 22 hours represents a generous amount of time between an ordinary exposure to moisture and one’s opportunity to clean the exposed firearm.

The results appear below, in order of my subjective ranking of best-performing to worst:

Breakfree CLPEezox Gun CareBest:
Break Free CLP: No rust, bright.
Break Free LP: No rust, bright.
Eezox: No rust, bright.
Sheath: No rust, slight darkening.

Very Good:
TW25-B: Trace rust freckling, slight darkening.
RemOil: Slight rust freckling on bottom.
3-in-One Oil: Trace rust.
Bore Cote: Trace rust on bottom.
WD-40: One small area of rust.

Rust Prevent: Two small rust spots, <20% coverage.

Arms Cote: >50% rusted.
Miltec-1: Significant rust along bottom; rust freckling on top.
Kroil: >75% rusted.

The results of the first test produced two immediate thoughts. One was that my first test was probably tougher than most real-world scenarios, as I had been using some of the lower-ranked products for years and had never seen a spot of rust. The other thought was to wonder what would happen to the better products with long-term exposure to salt spray. This led to test number two.

Test 2: Repeated Exposure

The second test was designed to see how the products would hold up to repeated exposure to a corrosive environment, so I changed the test to alternate wetting and drying. I also wanted the product application to be lighter, to be representative of the type of wipe-down many people leave on a firearm exterior before carrying it afield or concealed.

Test two started with two-inch bright finish nails cleaned and polished with steel wool, and degreased even more thoroughly than in test one. This batch of test nails sat in a bath of degreaser for 10 minutes after their initial spray-down with Gunk-Out and wiping.

Proceeding under the same test conditions as in test one, each test product was applied to a nail by wetting a clean, cotton patch with the product, and then carefully wiping down all surfaces of the nail. The nail was then placed on its gridded portion on the same sheet of wax paper. Again, two untreated nails were used as controls.

The sheet of nails was then misted with the saturated salt solution until uniformly coated, but not so heavily as in test one. Interestingly, while the two control nails attracted the spray and pooled it alongside, all of the products but one seemingly repelled the moisture on the wax paper from the nails.

The second test brought back the more promising and popular products, plus a few additional ones: Hoppe’s Lubricating (vintage 1970s), U.S. mil-spec “LSA” Medium Weapons Oil (made by Bray Oil Co.), and CRC 5-56 Lubricant. The latter is a spray commonly available in auto supply stores.

The test nails were allowed to dry, and the formation of salt crystals on all of the nails was then apparent. The nails were misted again with salt spray every five to six hours.

Observations were made after five (5) hours and after 29 hours. Again, I rank them according to my subjective observations:

Sustained Exposure After 5 hours After 29 hours
Eezox No rust, bright No rust, bright
Break Free CLP No rust, bright No rust, bright
Break Free LP No rust, bright Trace rust freckling
Very Good
LSA Medium Weapons Oil No rust, bright Some freckling, small rust spot
WD-40 Trace freckling Some rust freckling, few spots
RemOil No rust, bright Some rust freckling
TW25-B No rust, bright Some rust spots and freckling
Rust Prevent Trace rust freckling Significant coverage with rust spots
CRC 5-56 No rust, bright Freckling; rust strip 1/3 of bottom
Sheath Trace rust freckling Rust spots & freckling
Hoppe’s Lubricating Significant rust on bottom About 50% rust covered
3-in-One Oil Significant rust spots More than 50% rust covered

After noting my finding on the second test, I decided to see how long it would take to get Eezox and Break Free CLP treated metal to start to rust. I continued to mist the nails twice a day with the salt solution. Amazingly, after one full week, the Eezox nail was still bright and shiny, while the CLP started to show a mere trace of rust freckling. Clearly, Eezox was the winner of my tests, followed closely by CLP.

After writing up my notes on the second test, I returned to the work shop with my test nail sheet and decided that instead of unceremoniously dumping the nails… as I had done after the first test… I would see if I could get the CLP or Eezox to rust. Over the course of another week I misted the sheet with the same salt spray solution at least once, sometimes twice, a day. I was a little less scientific and methodical here, as this final round was sort of just for the heck of it.

Eezox Gun care ProductsTowards the end of the second week I started to notice some freckling on the CLP nail. By day seven of supplemental testing (and day 14 total), the CLP nail was starting to show light, but noticeable, rust coating most of the nail. Amazingly, the Eezox nail was still clean. It had a fair coating of salt crystals, but not even a trace of rust.

The test could have continued, but there was no point in doing so. Two weeks of repeated exposure to a heavy salt solution without cleaning and application of a preservative is a more extreme situation than any I can imagine finding with one of my guns.

Comments and Observations

I have used some of the products that finished fairly low in my rankings for years with no complaints. For example, although Birchwood-Casey Sheath finished near the bottom, I have used it for over ten years and haven’t found anything it allowed to rust. This may mean my test was unrealistically harsh. But it also tells me which product is more likely to fail first under extreme conditions. So while I’ll still use up the remainder of the Sheath and Rust Prevent I have on hand with confidence, I doubt I’ll need to buy any more. CLP and/or Eezox alone will supplant my cabinet full of products.

Despite its good results, I would not use WD-40 for firearms unless I had little other choice. The “WD” stands for “water displacing,” and WD-40 does that task well. That means it is good for hosing down and flushing out that duck gun that fell overboard, at least until you can get it home for a proper cleaning. However, WD-40 tends to gum and turn into a varnish with time. So WD-40 may be fine for an external wipe down, but it is potentially devastating to moving parts that require lubrication. In my experience, WD-40 has little, if any, lubricating properties, and is best left for its designed tasks.

Then there’s the issue of lubrication. Most of the products tested claim to be lubricants. My tests do not predict in any way which will be a better lube than the other. The same goes for products that claim to be cleaning solvents as well.

Interestingly, the products that claim to be primarily rust preventatives finished lower than two “all-in-one” products. Both top-finishers Eezox and Break Free CLP claim to clean, lubricate, and prevent rust. Some people claim that do-it-all products cannot perform any one job particularly well. But now we know that they are wrong, at least as far as rust prevention is concerned. And I have found Break Free CLP, and to a lesser extent, Eezox, to be decent gun cleaning solvents except where metal fouling is present. Both have also been satisfactory lubricants in my over 10 years using them.

Another interesting observation that ran counter to my expectations involved Break Free LP. LP is, as you would expect, the same as CLP but without the cleaning compounds. This should mean that LP should lubricate and protect better than CLP, which is “diluted” with “C,” the cleaning solvent. Maybe LP is a better lubricant than CLP, but it clearly is not a better preservative.

While many of the “premium” gun care products can be costly, one of the nice things about both top performers is that they can be bought in bulk-sizes. Buying pint or larger bottles of Eezox¹ and Break Free CLP can certainly cut costs over the more common smaller sizes.

And the best buy of all is CLP’s military predecessor, LSA. LSA can often be found for $1.00 per four ounce bottle. While it is not a cleaning solvent, and I can’t vouch for its lubricating properties, I would feel quite confident using it to prevent rust on any firearm. And considering I prefer to use a quality synthetic grease for the gun parts that need the most lubrication (e.g., bolt lugs, slide rails), LSA would likely suit my gun oil needs just fine.

Another consideration in choosing a gun care product is its affinity for dirt. That is, will it attract dirt, dust, pocket lint and other forms of crud? While 3-in-One oil showed that a thick coat will protect well in the short term, it would never be my choice for wiping down guns because it attracts dirt like a magnet. By contrast, Eezox, which mostly dries, and TW25-B, which can be wiped dry and still perform well, are much better at resisting dirt.


Lots of gun care and household products claim to prevent rust. Most do, to one extent or another. For routine use in normal situations, most of the products tested will serve just fine. I can say this because I have used these products over the years without encountering any rust problems.

But for those who are anticipating exposure to marine environments, wet weather, prolonged contact with sweat and skin acids, the higher-ranked products should provide that desired extra-margin of protection.

Finally, if you don’t see a product you like, or are curious about, listed in my test, just follow a similar procedure and test it yourself! Salt water and nails (or strips of ferrous metal) are cheap and readily available. That way you can find out for yourself just what works, and what doesn’t work. Just like I did.

Larry Pearson is an NRA certified pistol instructor and a member of the American Society of Law Enforcement Trainers, as well as a former police officer, former military firearms instructor and lifelong student of the martial arts. He also felt that he had something of value to share with the firearms community, and wondered which gunzines he should approach with the above essay. The problem was that he was dealing in ideas and concepts, and virtually all of the present gunzines only want articles about products and services so that their advertising department can sell space and everyone can make money. This is the American way. This is his first published work.

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