I'm working on cutting down my Leo Vince this afternoon and am having the most difficult tim drilling out the rivets on the end of the can. I'm basically working with a conglomeration of handmedown tools so maybe the drill bits I'm using are worn? My method so far is using a punch in the center of the rivet to give the bit something to bite on and then slowly drilling the rivet, which is giving me no luck. Buy a new set of bits or is my method incorrect? Thanks in advance for any help.