I noticed a recent forum post where someone was asking what corrosive ammo meant and thought it might be a good topic for a blog entry. Many people use surplus military ammo and some of it is corrosive. The primer is really the difference and the corrosive compounds are potassium chlorate, or sodium petrochlorate. When the cartridge is fired and the primer is ignited these compounds decompose into potassium chloride or sodium chloride. Now this will not immediately corrode your firearm, but can cause rust if left uncleaned.
So what to do, not buy the ammo? Nahh, the regime is either to wash and dry the parts and then clean and relube, or to use an ammonia based cleaner, dry, clean and relube. An easy to find ammonia based cleaner is window cleaner, yep, Windex. Spray, wipe and allow to dry and then clean as normal.
No need to be afraid of corrosive ammo, but if your practice is to only clean your firearms every third Saturday of a full moon, you may want to skip it. When using this type of ammo you should be cleaning after every trip to the range.
Here’s a couple of additional articles on the topic of surplus ammo with corrosive primers: