How to Keep Reloading Dies From Rusting

  • Written By Eric Crouch on March 29, 2020
    Last Updated: January 31, 2021

Reloading dies play a critical part in the reloading process, but they have to be well maintained if they are to seat and adjust your brass casings and bullets properly. One of the biggest things that affect die performance is rust, which can spring up suddenly if they aren’t treated or stored properly. Let’s go over how to keep your reloading dies from rusting.

Why Rust Happens to Dies and Other Reloading Equipment

To understand how to keep your reloading dies from rusting, let’s first explain why Rust is even a problem for your dies and other reloading equipment.

Most dies – and a majority of the components you’ll use to reload your own ammunition – are made with steel or a similar metal (sometimes even upgraded stainless steel). But steel is a metal that is mobile to rust, which is also known as iron oxide.

In a nutshell, rust is formed whenever iron and oxygen react while in the presence of water. This water doesn’t have to be in a pool of liquid; it can also be encountered in humidity from the air. This is why gunsmiths and reloading hobbyists around the world have difficulty maintaining their equipment if they live in humid environments compared to living in a dry environment.

As the metal of a die is exposed to oxygen and water, it begins to corrode and rust forms on its surface. This is technically a combustion reaction, though it’s not as violent as fire, so rust does not become hot or produce a flame. The presence of salt can also speed up the rusting process, which is why gunsmiths on the coast must be very vigilant about maintaining the quality of their equipment.

Rust eventually piles up on the surface of the metal and “consumes” the steel from top to bottom. Given enough time, any piece of steel will eventually rust and disintegrate entirely. This includes dies and other reloading equipment.

Therefore, the way to keep your reloading dies from rusting is to prevent the steel from reacting with the oxygen and water in the air. There are several ways to accomplish this general goal, which we’ll describe below.

Treating Dies to Prevent Rust

Firstly, preventing rust often involves taking steps to care for and maintain your dies before corrosion even begins to occur. If you take care of your dies properly from the moment you remove them from the box, they will last a lot longer compared to dies that you have to clean rust off of and maintain afterward. This can, in turn, save you lots of money over the years when you don’t have to replace gun reloading equipment that corroded too far to be useful.

The good news is that most factory-made dies are actually hardened and micro-polished to produce a mirrorlike finish. This makes them less vulnerable to corrosion right off the bat, but plenty of dies are also treated with a rust preventative before they enter the box to be shipped to your home or store. So most modern dies are at least somewhat rust resistant from the get-go.

Still, you should take steps to prevent rust from accruing as soon as you receive dies in the mail or buy them from a store. When you remove your dies from the box, it’s a good idea to clean them thoroughly before you use them for the first time. This involves taking out the assemblies, flushing the assemblies with degreasers or lubricants, and cleaning expander balls. In fact, you’ll want to disassemble every dollar you purchase and thoroughly clean it with a good degreaser and a cloth before doing anything else.

Make sure you flush out the interior of any die body with extra degreaser; don’t be afraid to use too much of this stuff, as you want your dies the last for a long time to come. After flushing out the interior of the body, you’ll want to dry the die completely with a clean cloth. You can then reassemble your dies and prepare for the next step.

The next step is putting a rust preventative treatment or light oil on the surface of your dies. This is especially important if you live in a humid environment, even if you try to store your dies in a dry place like a basement or garage.

Oil Examples

Which oils should you choose for this process? You have lots of potential options. WD-40 is a classic oil that many gun reloaders use to maintain the quality of their dies, especially since it’s something most people already have.

Or you can use something like the Cosmoline RP-342 Heavy Rust Preventative Spray. This effective anti-rust treatment is used by the military to prevent several of their components or weapons from rusting over time. You only need to spray a single coat to protect your dies for at least several months or even up to a year depending on ambient humidity.

This is a great pick for many reloaders because it’s easy to apply and is incredibly tough; the coating doesn’t crack or peel and can even remain a little flexible over time, which may be helpful if you plan to use the dies frequently.

You can alternatively purchase something like the Boeshield T-9 Rust and Corrosion Protection/Inhibitor. This is another anti-rust treatment. While it isn’t normally used by gun reloaders, it’s well known in the automotive industry, so it’s a great pick if you need an all-purpose anti-rust treatment that you can use for your other hobbies or things in your garage.

It eventually dries to a thin film that clings to metal for months, however, so it might be best for spraying on the exterior of your dies rather than the interior.

Either way, you’ll definitely want to apply something to your reloading dies to prevent them from rusting over time. This is true regardless of where you live and how well you store your dies to stop rust from accruing. Even the most sealed container can spring a leak and even the most careful gun reloaders can leave one of their dies out on a workbench from time to time. Having the treatment protecting your dies will ensure that you don’t need to clean rust off their surfaces no matter how you store them.

Proper Storage to Prevent Rust

That isn’t to say that storage is not important when it comes to preventing the corrosion of your reloading dies.


The biggest thing to keep in mind is placing your reloading dies in an airtight container. Preventing air from flowing in and out of the container that holds your dies will stop ambient humidity from constantly filtering in and out and settling on the steel surfaces of your dies. Air that is more humid obviously has more water vapor in every cubic foot, so it’s more dangerous for corrosion compared to drier air.

While sealing your dies into a container will also drop them with any ambient humidity within that container, it’s a lot better than letting your dies sit exposed to the air on a shelf.


You should also store your dies with cloths, or even some oiled patches, inside that container. Think of stuffing the interiors of your dies with expanding cloth lightly wetted with oil. This does two major things: it physically prevents water from touching the interior of your dies (and thus stops rust from accruing) and constantly applies a very small amount of oil to the steel surface.

Combined, both of these aspects will help to protect the interior and exterior of your dies even if you live in a humid location. Of course, ceiling your dies in an airtight container is even more important if you have high natural humidity wherever you live. But it’s also generally more important for reloaders to pay attention to this during the summer, when humidity goes up around the world.

Where to Store?

You can store your dies wherever you like, although many reloaders will stick their airtight containers in the garage along with the majority of their reloading equipment. This is normally a great place for reloading dies, as the garage isn’t well insulated and won’t retain heat very well. However, garages can also become humidity traps.

If your garage isn’t particularly well sealed and you live in a humid environment, you don’t need to give up. You can use a dehumidifier unit in your garage to lower the humidity of the immediate area around where you store your reloading dies. This won’t necessarily make a big difference for your entire garage, but it can be a lifesaver for a particular shelf or garage corner.

You can also make modifications to your garage, like installing a new window. This will automatically drink some of the humidity to the outside, preventing the interior of your garage from becoming as humid.

Some reloaders opt to bury their reloading dies, usually in a basement or cellar. This is a great idea if you want to escape humidity; it’s difficult for air below ground to become humid as it’s normally much cooler than the surface.

All in all, there are lots of places and ways in which you can store your reloading dies; it all depends on how much effort you want to exert to retrieve them and how long you need to store them. Just remember that the most critical thing is placing them in an airtight container and trying to protect them from ambient humidity.

If You Do Get Rust, Here’s How to Clean It

If you do see some rust on your favorite reloading dies, there’s no need to immediately panic. You can actually clean off rust fairly harmlessly and without seeing any drop in performance from the reloading die unless the rust has been there for a very long time; it takes a big patch of rust to affect seating and other aspects of a die.

If the rust is relatively light and new, you can always use a soft wire brush or steel scrubbing sponge. Or you can use a dedicated gun cleaning brushes like the Westlake Market 9mm Gun Bore Cleaning Kit. With these tools and others like them, they physically remove the rust thanks to their steel or nylon boar bristles, scrubbing away the rust like dirt or debris. Since the rust in this scenario is relatively new, it shouldn’t have any adverse effect on the die surface beneath.

If the rust has progressed a little more or you want to be very sure that you don’t scratch the surface of your dies, you just need to scrub the rust off using the same tools described above in combination with a light oil like WD-40. Even kerosene can work in some cases. Wetting the die with this oil and scrubbing with a steel or nylon brush should do the trick, as at the oil will weaken the rust such that it can easily be removed.

More significant rust build up will need to be removed with more oil and scrubbing. Or you can use a chemical treatment for your dies; Evapo-Rust is a good example. With this product and others like it, you’ll simply place the die(s) in a small amount of the solution, then watch is the chemical reacts with the rust to dissolve it away. An advantage of this method is that it doesn’t require any safety equipment and not a lot of effort, and it doesn’t damage the steel beneath the rust.

All in all, there are plenty of ways to handle rust building up on your dies. Just be sure to treat them properly likely outlined above so you don’t have to worry about rust coming back again next summer.


Figuring out how to keep your reloading dies from rusting is just part of the learning process. Reloading takes a good amount of work in preparation, but the rewards in both savings and ammunition customization are well worth it. Hopefully, now you see that keeping your dies in tip-top condition isn’t as hard as it may seem. Good luck!

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