The pound-out stuck case removers should have a long hex nut with inside threads that when turned down against the die will extract the threaded expander/primer pin rod. This will allow the press to push out a stuck case from an upside-down die using a steel rod pushed into die with stuck case.
A trip to your local hardware store to buy a drill bit, tap (size match drill), washers, & bolt (size match tap) will work. Anybody out there who has used the Frankford Arsenal stuck case remover? As good as I am, I still ger stuck cases, like 2-3 1-2 per year.
Just guessing - using a big vise to squash a case head, the nail thru brass flash hole would prevent the case from being collapsed/formed into an elliptical shape with the ends of the ellipse jamming into the die making the extraction more difficult.
My last stuck cases happened using a Lee F/L 6mm CM die on once fired 6.5 CM cases, despite application of case lube.