Most, if not all, drill bits will have problems going thru an existing hole. Drills are made to cut with the point or the chisel edge of the flutes. The outside edges will easily dull if the workpiece is not held firmly in a vise, or something like it, and the feed is not controlled. This is especially true when cutting SS grades like 304... they trend to work-harden if you cannot maintain a constant feed rate. most
vaping equipment is made from 303, 304 or 316 stainless steel. A hand-held drill is not the tool to use! Maybe try a Dremel tool with a small bit and carefully work the hole bigger? A reamer would be the cutting tool of choice, but not readily available to most people.