From Halopedia, the Halo wiki
The Mangler is a highly powerful handgun designed by the Jiralhanae and employed by the Banished. It heavily resembles a human revolver, with an 8 round swing-out cylinder reloaded using a speedloader-like device. It fires large spike rounds likely using an explosive charge or powder encased in red metallic cartridges. The Mangler also has two long blades under the barrel for melee attacks. Although extremely different in terms of functionality, the Mangler's appearance is highly reminiscent of the Type-52 Mauler.
The Mangler has an ammo capacity of 8 rounds.
List of appearances