Mike, are you still using the cut-off drill bit?
I only suggested that on the spur of the moment at the time, but I'd be interested to know if it feels smoother than the original bucking-bar, since it's made of harder metal.
The original bucking-bars, (hate that name, I'd change one letter), are made of soft steel and the cam bites into them, but that shouldn't happen with the drill bit.