Grumpy's handgun was the weapon brandished by Grumpy during the Gotham National Bank heist.
History
Grumpy attempted to shoot the manager, after being told the man was out of shells. When he emerged, the manager fired a shotgun at him, grazing Grumpy's shoulder with buckshot.
In the vault, Grumpy learned that Happy had killed his accomplice on the roof after they had finished their task, under the order of the Joker. Grumpy revealed that their boss had told him something similar, afterwhich he shot Happy as he turned around to face his attacker.
As they gathered the duffel bags full of money Grumpy aimed his gun at "Bozo", who was the Joker incognito, believing that the Joker told "Bozo" to kill him as soon as the money was loaded. He never got to kill his "accomplice" since the Joker's bus driver backed a school bus through a wall, knocking Grumpy down and killing him.
Behind the scenes
- It may be unverifiable what became of Grumpy's Glock 17.
- It may have been collected by the GCPD, the bank manager or his associates, or one of the bank's patrons.