If you're keeping it simple and using a single switch for the weapon then a set of RC switch + relays would do fine (plus some microswitches for end stops if the LinAc doesn't have a limit switch of its own) to just flip it between the battery voltage in either direction. You'd have to do some simple circuit design to get the receiver signal controlling it properly.

Alternatively, you could get a reversible brushed ESC but if your not worried about controlling the speed then you'd be wasting some functionality.