I had never heard of that, having owned a half dozen of these things over the years, cannot even faintly imagine why. I did look up the manual in question though...

http://www.leeprecision.com/cgi-data...uct/PT1023.pdf

...and it does say that. Why, I cannot imagine as all the driving parts are plastic (and therefore have 'give' far beyond the metal of bench or loading press priming systems), and are hand pressure only.