Originally Posted by
Doug Sewell
Go rent a Hilti hammer drill. I didn't believe how good they were until I used one. I was tyring to drill with a Dewalt and was getting nowhere then switched to the Hilti and it went through 30 year old concrete like butter. Oversize the holes and GENTLY screw the screws in. DO NOT try to overpower the screws or they will snap, use the clutch on the drill and things should improve greatly.
Doug nailed it here. we have a dozen or so Hilti TE-7's (the 7 replaced the 6 which replaced the 5); all work GREAT. If you can rent one of these models and purchase their 'Quick-con" screws w/ the hex head, you'll be well on your way to success.
I often had the same complaints about tapcons before I used the Hilti products. Yes they are expensive, but worth every penny. I only break 1 out of 25-30 screws.
Good luck,
NWB
"there is no such thing as a mistake in woodworking, only opportunities to re-assess the design"