Can you unlock the real mega buster in Dead Rising 2

In part 1 when you get the zombie genocider achievement (Kill 53,594 zombies) you get a message "Mega Buster Unlocked."

In DR2 when you kill 72,000 zombies to get both achievements you unlock nothing. So no. I hope they come out with dlc releasing the Mega Buster though for maybe 280 Ms Points!