On 5/8/2013 12:00 AM, Leon wrote:
Hard to say but a worn bit will slip out if the bit is past it's prime. For
many many years I have used the combo screws, non, plated that McFeeley's
sells with out issue. For the more heavily plated bits that McFeeley's
sells they offer a special under sized bit. I would suspect the plating
giving more grief than the combo head style.

You're more likely right, especially as I have no experience with the
older screws. The bit I use is quite new though. I have driven perhaps
200 screws with it.