Does anyone know of a resource for dating an early FN shotgun, serial #70xx. It is Browning model A-5, but there is no mention of Browning on the gun. It is a 16 gauge, originally chambered for 2 9/16" shells, which my Dad later had converted to 2 3/4". I believe it was manufactured for the European market as it has a Monte Carlo stock which you don't see in the US. Any help would be appreciated. Thanks!