Reloading Die Rust Removal

You find a great deal on reloading supplies. You reach out to the seller, and you set up a date and time to pick up the supplies. You meet up with the seller, chat for a bit but you are so excited about this great deal that you only do a cursory inspection of the equipment before handing the money over and loading it up in your vehicle. When you get home, you begin examining the components in great detail and notice that most of the dies have rust on them to some degree. Rust on the outside? Not a problem, the die will remain 100% functional so it is no big deal. Rust on the inside of the dies? Wicked big problem especially if it’s the sizing die and very annoying. There is always a tradeoff; cheap reloading equipment normally comes with some kind of elbow grease tax. 

So how do you knock the rust off? I have tried several methods and researched just as many. Some work better than others, and of course, your mileage may vary depending on how bad the rust is, the tools you have at your disposal, and the chemicals available to you. Now, something to note: if a non-carbide sizing die is rusted on the inside, you may just want to put it aside and use it for spare parts depending on how bad it is. After all, a sizing die with severe pitting on the inside could scrape, gouge or otherwise ruin your brass and/or not size it appropriately. We do not want brass that could cause some kind of problem in your very expensive firearm down the road, so I found that it is best to set them aside and to find a new die rather than to try and rehabilitate an old pitted one. However, this isn’t to say all rusted sizer dies are a lost cause. If you want to know more about reloading dies and the function of each, please keep an eye out for a more detailed blog post in the near future.

So the big question: what is the best way to get rust off of dies?

We have three mechanisms to remove rust: physical, chemical or a combination of the two. In my experience, using chemicals to remove the rust is optimal because it involves less work on my part. But it usually requires some kind of mechanical action such as scrubbing with a Nylon or bronze brush and so on. I have outlined some chemical and physical methods that I have researched or tried to do myself in the list below so please feel free to look through each method and come to your own conclusion about what would work best for your situation.

Please note that the chemicals used in some of these methods will produce toxic vapors, always perform this work in well ventilated areas with the proper personal protective equipment (proper gloves, respiratory protection and so on) before beginning work. And of course, if you are using a penetrant, solvent or other flammable liquid, don’t use it around open flames.   

Methods I have heard of or researched:

1. Soak the dies in Diesel fuel mixed with automatic transmission fluid: Basically, what it say. I have no idea what ratio Diesel to ATF to use but apparently it works if you allow the parts to soak for long enough. The rust simply falls off. I do not know if the dies become discolored or if the solution etches the metal. Use this method at your own risk.
2. Evaporust: Using Evaporust will remove the rust from your dies, but I have heard that it will change the surface finish to black. I do not know if this would affect how brass cases would interacts with the inside of the sizer die. I have heard that evaporust can etch the steel making reloading dies unusable. On the other hand, others have said they had no issues. So your milage may vary; be wise and do not use valuable dies until you fully understand the process. In my humble opinion, I would steer clear of this method with the multitude of other options available.
3. Electrolysis: This method is a little more involved than most since you have to have a battery connected to your pieces, and a large bucket to contain everything. If you decide to go with this method, make sure you do it in a well-ventilated area. I have heard it can be a bit messy and produce some less than desirable fumes. It will remove rust, but you have to keep an eye on the process and understand when to remove the pieces from the solution. Try it out on some scrap bits before de-rusting your potentially valuable dies.

Methods I have used or experimented with:

1. Tumbling in corn cob media: I grabbed a .22 Hornet die and tried spinning it down for several hours in corn cob media, but it never made any progress, and I quickly became impatient. Supposedly, adding mineral spirit may help but I didn’t have any on hand and I didn’t want residue getting into my only tumbler. This may work for some folks if you use some kind of a solvent, but I never took this experiment any further. It just seemed a bit too futile to me.
2. Citric acid bath: This one was interesting. Use a lot of citric acid mixed in water. I have no basis for ratio, but I used several tablespoon (5 or 6 I guess?) in about 2 cups of water. I used the .22 Hornet die I mentioned above. I allowed the die to sit for about an hour or so and eventually used a bronze brush to scrub the external rust off of the die and I noticed the die went from rusty to a light orange color. So, the rust came off but it discolored the die. This may not be desirable to some folks but if you don’t care about the appearance, this would work. I did not have the right bronze brush to tackle the inside of the die, but I imagine the results would be the same.

CAUTION: Do not stick your bare hands into the citric acid/water solution. Use acid resistant gloves to add, remove or work with the die or you will get chemical burns!

3. Soak in Kroil, Ballistol, or Hoppes No. 9: I prefer using these penetrants. I like soaking the dies (or anything that has copious amounts of rust) in Hoppes No. 9 for about a week, depending on the amount of rust and it normally falls off with minimal scrubbing (normally wipes off). I have used Ballistol but the smell really irritates me, so I only use it if I have to. Kroil is a good alternative from what I have heard but I have not used it.  

So now that we have gone through some options for chemical rust removal, here is a breakdown of the physical portion of rust removal. It is very simple: Nylon gun brush, pure bronze brush, Chorboy and Flitz. It is wicked important to use pure bronze: do not get a bronze plated brush otherwise you will scour the die. The whole point of the bronze is that it is softer than steel and will not mark, gouge or otherwise remove steel from the die. It is critical that the sizer dies inner diameter (I.D.) remains the same otherwise you will not get dimensionally correct brass.

So here is my method in a nutshell. Soak the die in some Hoppes No. 9 gun cleaner for a bit. It honestly does not have to be for a prolonged period of time. A few minutes to an hour is okay for most cases. Next, I use a Nylon gun cleaning brush (looks like a double-sided toothbrush) that you can get at any gun shop and scrub the outside of the die. Again, this does not take a huge amount of time, just keep soaking the brush in Hoppes and you should be good. If there are any tough spots on the outside of the die feel free to use the bronze brush. For the inside of the die, I use an appropriately sized bronze bore brush and scrub it really well. Some folks like to attach the brush to a drill, but I have not done this. Okay, so most of the rust is gone but there are still some annoying spots. Let’s get that Flitz out and some Q-Tips. Squeeze a generous amount of Flitz on the Q-Tip and scrub it into the rust spots for a long time. Wipe it away and see what the outcome is. If it looks better, then keep doing that. If it only looks marginally better, you can take the bronze brush, put some Flitz on it and begin scrubbing. This normally takes care of the issue after a few minutes but like I said, it is very dependent on the rust spot and if it feels like behaving. If the bronze brush leaves some scratch marks behind, then use the Flitz to polish it out.

This method above has worked quite well not only for dies but also with other rusty components like reloading press rams, case trimmer cutter shafts, and more. If you have any other methods or “know-how”, please let me know and I will include it in this post!