Whenever the term ‘corrosive ammo’ gets tossed around new shooters, most of them recoil like a vampire exposed to sunlight. They think that shooting corrosive ammunition is akin to dumping highly concentrated sulfuric acid down the bores of their handguns or rifles.

This couldn’t be further from the truth.

Although using corrosive ammo will corrode and pit the internals and barrel of your firearm, you can comfortably shoot corrosive surplus ammunition so long as you follow the proper cleaning procedures that we will outline in this article.

I hope you bought a can opener for that spam can of military surplus ammo because we are going to pull the trigger on some corrosive ammo and learn what it is, what it isn’t, and how to ensure your firearm is clean and protected from corrosive ammunition.

What is Corrosive Ammo?

Corrosive ammo is a bit of a misnomer as the ammo itself is not corrosive, however, the primers in this ammo contain a priming compound that utilizes corrosive salts. Once fired, these corrosive salts will be deposited in the barrel, gas system, bolt, and chamber of your firearm and begin to corrode unless properly and quickly removed.

How can you tell if ammo is corrosive?

Unless stated on the ammo container, all military surplus ammo that is Berdan primed should be assumed to be corrosive, while Boxer primed ammo will be non-corrosive.

To understand how corrosive primers came about, it’s a good idea to take a quick look at how centerfire cartridges, primers, and primer chemistry evolved over the years.

Evolution of Corrosive Primers

Between 1808 and 1812, the Swiss gunsmith Jean Samuel Pauley created the first centerfire cartridge which utilized a percussion cap as the primer. A percussion cap utilizes mercury fulminate as the priming compound as it is very effective at igniting black powder.

Although mercury fulminate excels at igniting black powder, smokeless powder exposed the shortcomings of the percussion cap.

Mercury fulminate will slowly decompose over time, meaning that eventually, the percussion cap will lack the energy required to ignite the smokeless powder. This was never realized as an issue with black powder, as black powder is so combustible that even static electricity can ignite it.

The next evolution of priming compound was adding potassium chlorate to the mercury fulminate to stabilize the mixture. However, this evolution presented new problems.

Higher pressure smokeless powder rounds would leave mercury deposits inside the barrel and the brass cartridge case. The mercury coating would embed itself into the brass, therefore weakening it and making reloading impossible.

The US Military decided to stop the use of mercury-based primers in 1898 and began working on a new primer system. Frankford Arsenal proposed the FA-70 primer that utilized potassium chlorate as an oxidizer for lead thiocyanate.

Continue reading Corrosive Ammo: Rust Inducing Nightmare or Cheap Plinking Fun? at Ammo.com.

I disagree highly with one statement here- boxer primed ammo used even by the United States prior to about 1950 is usually corrosive. ( many sites have complex charts that will tell you when various military manufacturers made the switch to non- corrosive priming essentially completed by the mid 1950’s)
And there is plenty of berdan primed ammo made that is non corrosive.
Primer type is in no way an indicator of corrosive priming at all.

I only shoot corrosive in bolt guns. A patch wet with Windex then clean as normal directly after shooting.

This thread should be in the ammunition section.

People get way too worked up about corrosive priming. Do you really think that the Russian soldier ran boiling water through his barrel five minutes after shooting at a German?

Your 91/30 isn't going to turn to a pile of rust because you shot a little corrosive primed ammo. Chances are that's what has been flying down the barrel for the last 80 years. Just clean it and you'll be good to go.

quote:

Originally posted by kz1000:
I only shoot corrosive in bolt guns. A patch wet with Windex then clean as normal directly after shooting.

Note to others, make sure the Windex has ammonia in it. There are some formulations that do not contain it.

quote:

Originally posted by sigcrazy7:
People get way too worked up about corrosive priming. Do you really think that the Russian soldier ran boiling water through his barrel five minutes after shooting at a German?

Your 91/30 isn't going to turn to a pile of rust because you shot a little corrosive primed ammo. Chances are that's what has been flying down the barrel for the last 80 years. Just clean it and you'll be good to go.

Depending on where you live and how humid it is can make a big difference. I have seen rust start in a barrel in 24 hours here in Il when the humidity is 75% plus!