Re: neck turning question
I've got the K&M and use their caseholder in my B&D cordless screwdriver. I've found with my set-up, if I remove the caseholder from the screwdriver and rotate it and drop it back in the screwdriver around its various six sides, I can reduce the wobble quite a bit. I just load a case into the shellholder and keep rotating the caseholder to each of the six different "sides" in the screwdriver (hitting the power button in between each time and watching the brass wobble, less hopefully). I only do this once, not for each piece of brass.
I hope the above made some sense.