The DB Shotgun is semi-automatic in Carnivores: Dinosaur Hunter. It was probably removed so the iPhone did not have to process the reload animation, most likely the reason Double Ammo was removed also. This does, however, make the DB Shotgun a much more effective weapon, and actually worth the 150 credit price. The most recent update of Carnivores: Dinosaur Hunter, however, brings back the DB Shotgun's reload animation.
The DB is also louder than the Shotgun, and can even scare off carnivores such as the Ceratosaurus at a distance.
If debug mode is activated, the character will only fire once, and reload both shells.
The Poacher in Carnivores Ice Age carries a DB Shotgun.