Cleaning After Corrosive-Primed Ammunition

Lots and lots of people have bought or are buying ammunition made somewhere in Europe, mostly 7.62x39 and 7.62x54r, sealed in ‘spam cans’. This ammo is generally quite reliable, reasonably accurate, and sealed up in that manner it’ll store for years without problem. If you use some of it, though, you will need to clean your arms properly afterwards. It’s not referred to as ‘corrosive primed’ for nothing, after all.

One detail first: the ammunition itself is not actually corrosive. One of the chemicals used in the priming compound leaves traces of salt behind in the barrel (and the action of a semi-automatic) when it ignites. The salt attracts moisture, and that is what causes the corrosion. Most modern cleaners are not designed to remove that salt, so you can clean, oil, and still get rust in very bad places.

Cleaners
What does clean out this salt? At its simplest, water. People used water to clean black powder muzzleloaders and cartridge firearms for a long time. Fortunately, we now have some things that work better:

• If you want to buy stuff, any cleaner designed for black powder will work (Thompson Center #14 for instance).
• Windex makes a window cleaner with vinegar; some people dilute it with three parts water and say it works very well. (I pour straight Windex down the barrel of my Mosin and I've never had a problem with my barrel corroding. -- Editrix)
• Want to make it yourself? Household ammonia (many people recommend the sudsy variety) mixed with one part ammonia to three parts water. You can dilute it further if the smell is too strong. 
• You can also mix some vinegar with water (there’s no hard & fast answer to ‘how much’, all I can find is a ‘weak solution’).

My favorite is Ballistol. This stuff was developed in 1904 as a cleaner / lube / protectant for the German army, with one aim specifically being to clean out the residue from corrosive primers. Its use is simple: take a bottle, put in one part Ballistol and add ten parts water, cap, and shake; this gives you a milky-looking cleaner that cuts that fouling beautifully. Use this solution to clean the bore and any parts exposed to the fouling, then dry it and lube with your favorite oil (yes, Ballistol is now a lube as well, but there are better ones now).

How to Clean After Corrosive Ammo

For cleaning a barrel:

1. Get a patch wet. Not drippy, but wet. 
2. Use a cleaning rod and a proper fitting jag and push it through the barrel. 
3. Let it sit for a few seconds, then repeat. 
4. Run a dry patch through, then an oily one. 

That’s it. If you want to really scrub it out, after the dry patch run another couple of wet ones through, then dry, then oil.

For cleaning the other parts of a firearm:
Bolt-action and single-shot rifles are easy because the cartridge case keeps the fouling in the bore.

1. Use a damp patch to wipe off the bolt face, then dry it, then wipe with an oily one. 
2. Clean the rest of the bolt and action same as you usually do.
3. If you’re worried about the chamber, take a bronze or brass brush, wrap a damp patch around it, and use it to scrub, then dry and oil.

Semi-auto firearms are a bit more involved because the gas that operates them can carry traces of the primer fouling. Use a damp cloth to wipe the gas tube or piston down, then dry, then oil where appropriate.

And that’s it.