Ive tried 1/2 and 1/4 inch non core core bits on a handheld core drill and they are NOT lasting long at all. One I made last 20 holes or so and the other 2 bent in less than 10. Insted of binding up the drill when I get off center they are just bending them. They are monster brand and are quite a bit cheaper than most others but I dont want to spend more on better bits if it is stupid to be hand drilling with no rig with such weak and narrow bits. Any suggestions? I cant get a rig in on this particular situation. The best I can come up with is buy 6 or 7 bits and try a keep a steady hand... which sucks.