Why are corrosive primers/ammunition bad?
For non-mercuric corrosive primers, the primary corrosion culprit is potassium chlorate (KClO3). Potassium chlorate was used as an oxidizer, providing oxygen, to the primer compound reaction. When the reaction takes place, the oxygen is removed from the molecule leaving potassium chloride (KCl). Potassium chloride is a salt much like sodium chloride (common table salt). The potassium chloride reside left in a gun barrel absorbs water from the air and creates a corrosive film responsible for barrel rusting. Since potassium chloride is highly soluble in water, this is the reason why it is recommended that barrels be washed with hot water after shooting corrosive ammunition. It is also recommended that shooters wash their brass that contained corrosive primers in the same manner.
