Plot device question - could you stop a .380 ACP round with a briefcase full of tightly wadded money? You can assume FMJ and a medium power cartridge.
Probably, but don’t try it. 
I have shot phone books with my Makarov, which is chambered for the sorta-similiar 9x18 round, and the phone book handily stopped both HP and JHP rounds.
Err, JHP and FMJ, not HP and JHP. :smack: