There is a very, very big difference in shooting holes in a ship's belt and sinking it. In order to sink a ship, it must take progrerssive flooding and this can only happen with serious damage below the waterline, something that is exremely rare by shelling, but is common with torpedoes and mines. Bismarck has neither, so NO SINKING, unless a weakly armored part adjacent to a magazine is pennetrated and blown up as a result, like on HMS Hood. In the whole of WW 2 the only active battleship vs battleship kill is HMS Hood. No other BB encounter had the dreamed result fo a BB killing another BB alone. (Even Kirishima was finally scuttled by her crew, rather than direclty sunk by USS Washington.)
That means a simple thing: BB's shells can hurt a modern battleship, but fail in destroying it by sinking. Only a catastrophic anount of underwaterdamage can kill a BB by sinking, which is either a very large explosive device, or a ship's hull desintegrating and loosing bouancy. Shells and especially AP shells have only a marginal explosive power comared to more effective weapons, such as torpedoes and mines.