You should be able to drill thru hardened steel with HSS drills if you keep the speed slow enough.(15 sfm or 5 Mm is only about 100rpm for 14mm) the problem with using a drill as a reamer is the tip is unsupported and will grab and chatter. Try screwing in a piece of soft bolt thread(allthread is even softer), put something underneath to stop it turning and then drill to the size you need, - this will support both cutting edges and stop the chatter.
Hope this helps
Nigel