I still have one BSS that is like this, and has been as long as I have owned it. Some of them were fitted using the forend to pull the barrels snug to the hinge pin Thereby leaving the barrels not seated on the breech face. The forend loops are silver soldered on so this works. It is not right , but it does work. I'd work on the forend iron fit to pull it tight against the pin again. Don't try and have someone weld up the hook and refit as the lumps were brazed with some alloy rather than silver soldered. Been there...

Dennis Potter