An attachment arrangement for a gun module of a carrier, such as a vehicle, a craft, or a structure fixedly mounted on a foundation, including, fixedly mounted on the carrier, a carrier frame. The carrier frame has at least two elongated frame portions, and the attachment arrangement includes an intermediate beam, on which the gun module is arranged. A subframe is arranged on the carrier frame, and a pair of interacting mounting plates are arranged on the subframe and the intermediate beam respectively. A weapons system includes an attachment arrangement and a superstructure module having storage spaces on top of the subframe.