So, I just got my Op:Hades book, and playing allies, I automatically went over to what the allies got. Under upgrades, there's an allied Upgrade to turn M9 bazookas into M9-D bazookas. However, after looking through the main rulebook the two expansions, and the Erratta, I can't seem to find any in-game difference between an M9 and M9-D bazooka. They're both bunched together in the core rules and neither have any special abilities for it.
At the moment, am I paying 1 AP for nothing? Or am I missing something?