Malvin,
Your description brings up the possibility that the forearm may be one of the "3 piece"types.Are there threaded holes in the ribs,by which wooden pieces can be attached to the barrels?This type forearm allows the same forearm "iron" to be used on different barrel sets( dbl shotgun/dbl rifle/combo)with panels attached to the barrels, to finish it out. It would be very helpful to have photos.
Mike