Platt was hit at least twice in the chest, one going through the arm first.
To get your facts straight on Miami, this is a good place to start:
"A perception that many have held the intervening years is that the eight FBI agents' marksmanship was gravely lacking. Not so, argues Dr. Anderson, and presents a persuasive brief that a number of FBI hits were good ones; they just happened to run up against two highly trained (military police, 101st Airborne and Rangers), well-practiced (approximately 750-1,500 rounds per week which they had purchased or robbed from several unfortunate civilians plinking in the Everglades), and extremely focussed individuals in Platt and Matix. The FBI fired a verified 70 rounds (possibly as many as 77 or 78) and delivered 18 wounds to the bad guys, firing at extremely hostile targets obscured by gunsmoke, considerable amounts of dust and debris from the crashing, careening cars, and the deep shadows of the trees beneath which their vehicle came to rest.
Among those wounds, McNeill hit Matix with that head shot plus a neck/chest shot early on in the fight; Dove delivered that difficult hit as Platt was wriggling from the passenger window of the Monte Carlo, as well as two others; Risner (from 30 yards!) also made a lethal chest wound on Platt in mid-fight; and Mireles, after his shotgun blast had delayed Platt with four 00 foot wounds, had one-handedly put three rounds into Matix's head and two into Platt (one central nervous system, one scalp) all while himself gravely wounded."