Hyper Magnum

Hyper Magnum is a firearm.

Source
Hyper Magnum can be found as a collectable inside the Fort Vaullerey compound, north of the main base structure (which is where the map will switch from overworld to dungeon format; the gun is on the overworld map) by the eastern gate that runs nearly parallel to the river. It can also be found in the Keycatrich Trench maze. Both of these are only available during Chapter 15. It can be sold to shops for 6,000 gil.