They were not impact bits but I had never used them with an impact before. I was never a power tool guy thanks to my military aviation training and it took a while to break that silly habit.Good to know about HF bits. Work hardened the bits so quickly- must have used them frequently in the past? Were they intended for impact use?
It was just a rotor hold down screw so pretty light duty even though they were rusted. The Ryobi just hammered away - you could feel the bits get hot. The Dewalt rattled for a half second and out they came.