Primers are important components of ammunition. But what are they made of? How do they work? Basically, a primer is some shock sensitive explosive mixed with other fuels, oxidizers, abrasives and binders.
The most common compound used to initiate the explosion is lead styphnate. Needless to say, it’s pretty toxic, which is why people say to wash your hands after shooting or handling ammunition. Primers made from this compound are considered to be non-corrosive.
The original compound used for priming was mercury fulminate. Its main disadvantage is that it produces elemental mercury, which readily forms an amalgam with brass, substantially weaken brass casings. In more modern corrosive ammunition, it was combined with potassium chlorate, which when ignited would coat parts of the firearm in potassium salts, which attract moisture and promote corrosion very rapidly if not removed.