I destroyed a decapping spindle by using the incorrect shell holder with my Hornady neck sizing die.
The die had initially been set-up with a Lyman shell holder. The next time I tried to size some 204 Ruger cases, I inadvertently inserted a Hornady shell holder into the press arm, which is 0.04” thicker than the Lyman shell holder. Thus, the sizing button made contact with the bottom of the case head during the power stroke - - oops!
The Hornady die does not make contact with the shell holder during adjustment, so it's easy to make this mistake if one doesn't pay close enough attention or is Brain Dead like I am.


Here's the pics: