When we originally tested our unique shell holder design, we full length sized two-hundred once-fired 300 H&H Magnum cases dry and unlubricated. We neither pulled the rims off the cases nor did we stick a case in the die. The heads of the cases and rims were unmarked by the shell holder jaws because the shell holder actually floats and permits the cartridge case to find its exact center in the die. When a case is in the shell holder it's supported by spring loaded jaws which contact the base of the cannulure for more positive extraction. The shell holder is also self acting, so when a cartridge is placed in the die and the handle of the press is activated, the jaws can open and close on the cartridge case. When the handle is raised, the jaws automatically open and release the case.