Used in a hand drill, it's not hard to break through the coating and then you just have a plain HSS bit.<BR><BR>I've used cobalt bits to drill the case hardened head on allen bolts for safety wire ...

DeWalt's Black and Gold drill bits are made from a type of tool steel known as High Speed Steel, often abbreviated as HSS. While HSS is a common base for a variety of drill bit types, it's ...