Dum Dum is a city in India
"During the 19th century the area was home to the Dum Dum Arsenal, a British Royal Artillery facility. It was here that, in the early 1890s, Captain Neville Bertie-Clay developed a bullet with the jacket cut away at the tip to reveal its soft lead core (see hollow-point bullet), known informally as a dum-dum[4][5][6][7][8][9][10] or more correctly as an expanding bullet. The previous name of Dum Dum was "Domdoma". " https://en.wikipedia.org/wiki/Dum_Dum