just now there is a lee 240 grains mould in auction here. thinking about this but the bullet need a gas check in any case. http://www.egun.de/market/item.php?id=3959716
I fear any load working semi-auto will be to hot for lead bullets.

if its possible to make bullets of 9mm parabellum brass ?

I will make an .375 insider expander and a mould for casting .375 lead core's. than press the core into the case in the rock chucker and resize to .407, ready!?
this rifle is more or less a fun project for my son and he will shot it at 50 meter's only on paper. if there will be some work for him before, good for him!