I was looking at this gun for sale yesterday, not up on British guns. it was in an old beat up leather case but the gun itself was well used but tight and in basically good shape. what seemed unusual to me was the number 3689 was on the water table and forearm iron but 5797 was on the underside of both barrels and on the trigger guard. also it had blued steel barrels, not Damascus. seller claims pre 1900. anyone know of a good source of info on these guns?

thanks!