Why Stainless Isn't Always Stainless
“Stainless” isn’t always stainless. Due to the machinability requirement of gun barrels, manufacturers are limited to using 416R Stainless Steel. Technically, 416R is a ‘stainless’ steel; however, the composition contains much higher levels of iron than higher performance grades of stainless steel. The iron in 416R is quickly oxidized, leading to rust much sooner than most firearm owners realize.
In contrast, Cerakote® is a thin film ceramic based coating that provides corrosion protection up to 184 times longer than 416R Stainless. In salt spray corrosion testing (ASTM B117), 416R stainless steel shows signs of corrosion within 24 hours. Under the same salt spray conditions, a sample of mild steel coated in Cerakote H- Series Firearms Coating showed no signs of corrosion even after 2000 hours."