Reba II

Reba II is a unique weapon in Fallout 4.

Location
In the Rook Family house, in the town of Salem, in a locked back room in the basement. Can be obtained after helping Barney Rook by activating his turrets, killing him and getting his key or stealing it after he invites the player into his house.

Behind the scenes
The gun bears a striking resemblance to the weapon used by Reba Mcentire in the film, Tremors. The additional damage to mirelurks and bugs may be a reference to that film's "graboids"