How to Test for Corrosive Ammo

Here’s a quick step by step to test if ammo is corrosive, and test your cleaning system against it.


A nail bed is a series of nails in a piece of wood that you’ll use as your sacrificial metal to check for corrosion.

  1. Clean off steel (non galvanized, non aluminum) nails that have enough room to fit into your test cases (no big nail heads)
  2. Pound them into a piece of wood, or drill the wood and slip them through (my nail heads were too big, so I opted for the pointy end through drill holes)
  3. Clean off the nails with scotch brite or steel wool
  4. Number the nails (not immediately beside the nail because that’ll get crud on it from firing the primer

Prep your cases by pulling the bullets out and dumping the powder. The primer contains the corrosive salts, so you just need the primed case.

Wear protective equipment like safety glasses, ear protection, gloves, and anything else you need to feel safe. Primers aren’t super powerful, but you don’t want to catch shrapnel in the eye.

Fire Corrosive Cartridges onto Nails

This next part is best done in a garage or the great outdoors. Fire off the primed cases on the nails. If you have a bolt that you can remove from your rifle, that can be an easier and more controlled way to fire the primers. I found it really easy to put a primed case into my SKS bolt, place it over the nail, and give the back of the firing pin a light tap with a hammer to have the primers go off.

Test Cleaners/Oils/Cleaning Procedures

Document your testing procedure and products and proceed to apply your test products to the nails in the same way. Make sure to leave 1 nail that is hit with corrosive and not treated at all and 1 nail that is not hit with corrosive salts so that you can be sure that it’s not just your humid basement causing everything to rust.

Yep, that’s urine in the cup

Observe Results

You’ll see clear results on non-treated “control” nails within a day, but I found that 3 days was all I needed to get conclusive results from the rest.

Learning 1: Corrosive Ammo Rusts Fast

The moral of the story on corrosive ammo is that it rusts FAST and rusts pretty deeply within a few days. If you clean it within 8 hours, you may just have a light flash rust to clean off, but if you wait more than 24 hours, there’s going to be real, unavoidable rust on your rifle.

Learning 2: Your Cleaning Regiment Must be Thorough

Just dabbing the nails in the products didn’t help. They will all rust unless the corrosive salts are removed. That means getting your barrel nice and wet with water or a dedicated corrosive cleaner, and following up with dry patches and oil. It also means cleaning out your gas system with pipe cleaners and the same products, and your bolt/bolt carrier should be cleaned too. None of it can be skipped. The corrosive cleaner did what it was supposed to!

Learning 3: This was Easy and Fun

I love experiments, and this was really easy and fun. I’d really encourage you to try experimenting with your own cleaning products and see what you find. As always, you are responsible for your actions and if you choose to do your own test, you are responsible for the outcome, not me.

What we’re trying to prevent

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