Reba II

Reba II is a unique weapon in Fallout 4.

Location
In Barney Rooks' family home, in the town of Salem, in a locked back room. Can be obtained after helping Barney by activating his turrets. Or by simply killing him or stealing it after he invited you 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"