First off,you must really tighten the nut that holds the pin,as you call it.I mean real tight!!!!!!!!!!!!!!Next,you must put alittle lube on the inside of the case neck!
Man,you won't belive how tight you must make that pin nut?Use two wrenches to do it,not the press.
Been there and done it!!!!!!!
been there too except the expander ball/decapper rod was pushed the other way (up) trying to decap some pmc 223 brass after that happened i realized pmc crimps their primers into the case.... Oooops!! after resetting the expander ball/decapper rod I didnt get it tight enough and it pushed up again just decapping some federal match 223 brass......... When we say tight you have really tighten it somewhere in the ballpark of about 75 to 85 inch pounds.