Corrosive ammunition is ammunition that uses a primer with chemicals that, when ignited, leave a residue of corrosive salts.
Most often, these primers have potassium chlorate or sodium perchlorate which, when burned, decomposes into potassium chloride or sodium chloride.
Sharp-eyed readers will note that sodium chloride is also known as common table salt.
Potassium chloride isn’t much different than common table salt and both are very hygroscopic (meaning that they attract water) and, because of that, are highly corrosive.
We’ve all seen what salt water does to metal. The same thing happens to your rifle when it is left uncleaned after firing corrosive ammunition.
What Is Corrosive Ammunition?
Potassium chloride and sodium chloride are pretty harmless alkalis, but when exposed to the hydrogen and oxygen from the ambient humidity in the air, they can form a powerful acid that will cause the steel in your rifle to rust and pit.
Most modern ammunition is not corrosive, but old military surplus ammo is different. For surplus ammunition, there are two main types of primers: Berdan and Boxer.
Boxer-primed ammunition is not corrosive, so you don’t have to worry about it. Not all Berdan is corrosive, but almost all of the surplus ammunition you find on the market with Berdan primers is corrosive.
If your ammunition is Berdan-primed, it’s better to be safe than sorry and treat the ammunition as if it is corrosive.
It won’t hurt your rifle to clean it, so it’s a good idea to thoroughly clean it to get any salts out any time you’re shooting Berdan-primed ammunition.
Cleaning and Maintenance
In the past, when corrosive ammunition was standard issue for the military, soldiers would simply rinse the gun with hot and soapy water.
Since the corrosive salts are hygroscopic, they readily dissolve in the water. The basic solution of soap and water also neutralizes the acids created by the corrosive salts.
The firearm would then be dried out and re-greased or lubricated.
The same method can be used today after a trip to the shooting range. First, you should always make sure that your firearm is unloaded and safe. Then, simply disassemble your rifle and immerse the parts small enough to fit in a basin of hot, soapy water.
For the barrel or other parts too large to fit, you can carefully rinse out the part by pouring the soapy water over it. Once the parts are removed, the hot water will quickly evaporate.
WD-40 or some other water-displacement fluid can be used to make sure no water remains in the little nooks or crannies on the rifle.
If the thought of soaking your precious rifle in soapy water doesn’t seem like something you’re comfortable with, you can use an aqueous solvent like Hoppes 9 Plus or Shooter’s Choice Aqua Clean.
Both of these cleaners are water-based and have solvents that will dissolve the corrosive salts. In addition, they will also work for the general cleaning of your rifle, as they will remove carbon fouling and buildup.
Don’t forget to properly swab the bore with an oily patch, and oil and lubricate your firearm after cleaning.
Conclusion: Corrosive Ammo
Corrosive ammunition is perfectly fine to use. The corrosive surplus ammunition on the market is a great and inexpensive way to enjoy your military rifle.
By properly cleaning your rifle after using ammunition that is or is suspected to be corrosive, you can ensure that your rifle will have a long and corrosion-free life.
Do you shoot corrosive ammunition? Why or why not? Let us know in the comments section below!
Editor’s note: This post was originally published in July of 2010. It has been completely revamped and updated for accuracy and clarity.
As a reloader, I have had excellent results making target ammo by recovering components (bullets and powder) from corrosive Russian surplus 7.62x54r for my Mosins, and loading them into real brass shells with Winchester large rifle primers. I use a pin punch to safely pop the corrosive primers and scatter the empty copper washed steel cases arojnd my property to foil any possible future metal detection.
Years ago I had a chance to buy some old ammo cheap, still in the box and looking new. I was not sure if it would be safe, so I asked a friend who was the first to explain corrosive ammo to me. This was some old Spanish stuff, Berdan primed, but only ten cents a round. When my friend explained what I would have to do, I understood. I took it all to the range and shot it up, and cleaned that gun in a bathtub.
My friend assured me to use as hot and soapy water as I could, and then I oiled it down, wrapped it up, and put it away. A few years later, somebody wanted to buy it from me, so I unwrapped it, wiped it down, and looked just like new, with a clean bore.
Sounds like good info. Except one thing. WD40!! You forgot to mention NOT to use WD on blued surfaces. If it removes rust, it removes blue.
SPQR is correct. I still have some of the older government 30-06 that has corrosive boxer primers. I also have several older hunting rifles in various calibers with damaged bores from corrosive ammo common years ago.
Good article. i take exception to one point in it. WD-40 does not displace water, WD-40 is hydrophilic, which means it takes in water. So if you use WD-40 on a firearm you need to flush the WD-40 off of it or the WD-40 will retain the moisture and then rust you weapon. This is also true when used on bolts and other hardware. So it is best remove the WD-40 and replace it with your favorite firearm preserving oil.
I asked my master gunner (ret) friend how to clean after corrosive ammo. He said put the muzzle in a bucket of warm soapy water and run a cleaning patch up and down from the breech to pump the water through the barrel.
Others note that spraying the barrel with some ammonia window cleaner at the range will help too, and buy you some time to get home.
I have been using Sovbloc corrosive ammunition in my Mosins and WWII surplus ammunition in my Enfield and never had a problem. Years ago I was given a technique to use when shooting black powder revolvers, and it has worked equally well for me at the range when shooting more modern and possibly corrosively-primed ammunition. (The Russians still like corrosive primers for military arms because — so I have been told — corrosive primers are far more reliable in cold weather conditions with a temperature significantly below zero.)
1. When done shooting, but while the bore is still hot, remove the bolt. Clean the bolt face liberally with Windex. Also liberally spray Windex down the bore.
2. Run Windex-saturated patches through the bore until they come out clean. Then run dry patches until there is no blue color, indicating Windex is still there. Clean the bolt with dry patches until they are clean.
3. Saturate a patch with oil and run it down the bore; also coat the muzzle with oil. Oil the bolt face.
4. When home, clean normally. I generally use my own mix of Ed’s Red unless I need to remove copper.
That’s it.
Many years ago, bought a case of surplus GI bore cleaner. This was for WWII era GI ammo, which had corrosive primers. Now shoot some surplus Czech ammo, and it has corrosive primers. As I use up the last of the GI bore cleaner, nice to know that there are good options available.
Second on the recommendation for Ballistol.
Smells like dirty socks but you mix it with hot water and give your rifle a bath.
Rinse with the hottest water that you can stand.
Dry with compressed air or a blow dryer,
Liberally apply wd-40 or something like that, wipe out excess and relubricate with chosen high quality product and your good to go.
I have some M-67(?) 7.62×39.
Great ammunition, much more consistent than cheap steel case stuff but unfortunately corrosive.
My AK’s all still look pristine.
Corrosive primer are not the only thing that causes corrosion. Some gun powders will will corrode right through the brass cases while sitting in storage under normal conditions. I recently had examined 9mm ammo that I had loaded with Vhitavori N340 10 years ago with new brass and bullets and federal primers. The powder corroded right through the cases. The exact same bullets during the same time and stored next to each other were made with Winchester WAP were pulled apart and showed zero signs of corrosion.
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when shooting a military surplus rifle, how do i know if it is safe to shoot or not? with ammo being corrosive, could that potentialy make the rifle unsafe?
CTD should start selling BALLISTOL! It works well with corrosive ammo. And I would rather order it from Cheaper than dirt.
“Since the corrosive salts are hygroscopic, they readily dissolve in the water.”
Like silica gel?
Those two things are unrelated. Fact remains that they are both readily soluble in water.
“Boxer-primed ammunition is not corrosive, so you don’t have to worry about it. “
This is not correct. There is a lot of Boxer-primed corrosive ammunition available that is corrosive, the largest example being US Army surplus .30-06 prior to the conversion to non-corrosive priming in the early ’50’s.
“aqueous” English please. 🙁
I have been shooting corrosive ammo. for the several years now. That is about all I can find that is cheep enough to shoot on a regular basis from my M44. Just clean it well, and don’t forget the bolt face, when you are done and you will have nothing to worry about.