I recently bought a K&M setup for neck work to use with a power drill. I found the shell holder to be horrible to clamp down,loosen and position case head as it is small sharp and has no grips..other than putting in an allen wrench in slot as in the instructions. I wasnt happy at all with this lame engineering and was thinking about having a machinist make a knurled collar for me to slip over the head and then I looked at a pack of forster aluminum die rings sitting on my bench. Perfect fit! now process is speeded up 3x and no more cussing at k&m.