What is a BBF? I have a CZ587 in 12ga/7x57R. Very nice gun and with scope is pretty accurate with Sellior & Bellot 7x57R ammo. I have the factory scope mount and it also works pretty good and returns to zero nicely. Don't think I have ever fired the shotgun barrel. I was always going to take it to Africa for guineas and plains game but always had a better idea when the time came and it never made it.
Its short for the German term bockbuscheflinte, which means stacked rifle shotgun...Over and under rifle shotgun combination gun.