Brother Mouzone tells Cheese after shooting him with a rat pellet round that his next round is a "120 grain hot street load" of his own manufacture.
9mm ammunition comes in 115,124, and 147 grain rounds which BTW is the weight of the bullet not the propellant charge as Brother Mouzone's statement implies. A 120 grain round load would actually be somewhat less effective than a slightly larger 124 grain round and more importantly would easily identifiable if the police were able to recover it from a body.
However, Brother Mouzone uses a Walther PPK .380, not a 9mm.
However, Brother Mouzone uses a Walther PPK .380, not a 9mm.