The truth about corrosive primers

[Robear]

There's a lot of misinformation about corrosive primers in centerfire ammunition. Here's the truth. Modern ammunition is made with non corrosive primers. But for many years primers were made with potassium chlorate. This chemical ignites easily, is reliable and inexpensive. There's still plenty of old military ammunition around with chlorate primers. Com block surplus 7.62x54R is notorious for this. Unfortunately these primers when fired spray the barrel with potassium chloride. This is a chemical similar to common table salt, sodium chloride. It is hygroscopic, meaning it quickly attracts moisture from the air. This damp mixture is highly corrosive. It causes the barrel to rust. Depending on the humidity and temperature, the rust could start to form in just a few hours. The rust causes the barrel to pit and lose accuracy. Fortunately potassium chloride is readily solvable in water. Any water based cleaner will remove the potassium chloride and stop the corrosion. The cleaner isn't "neutralizing the salts." It's simply washing them out. In the past shooters would pour boiling water down their barrels to clean them. This would remove the potassium chloride and the heat would dry the barrel. Old US military bore cleaner is water based and removes the potassium chloride. But any cleaner with water in it will do. Personally I use 20% Simple Green from the supermarket followed by Ed's Red. Ed's Red is a home brew cleaner containing acetone which leaves the barrel dry and lubricated.

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[boattail]

I learned about corrosive primers the hard way. I shot a bunch of old 45 acp in my Blackhawk revolver, that was in pristine shape. Shot it and put the gun away dirty. Opened the safe a month later and about died when I picked up my revolver. I managed to clean the rust out and saved the gun. The barrel is fine and still shoots great and looks good on the inside. The inside of the frame near the gap shows some rust colored tint through the blueing and no other signs of my F up. That gun is now one of my carry guns that gets to see regular use and not be worried if I get blemishes on it. It now has lots of holster wear and real use character. No longer a safe queen. I got a new safe queen to replace the Ruger.

I still have a few hundred rounds of that old ammo around. I may shoot it just to get rid of it ….then clean the gun this time!!!