IT happened to me yeasterday when i attacked one convoy twice (the escort was a lone HMS Rodney) .
Long story short i was atleast 9km away and waited rodney to sink (it sank later and got the credit) when i surfaced to finish off a merchant who also was hit by a torp but i dint have any left and used by deck gun.
I fired 2-3 shots max before the BB began flashing and shell fell around me, luckly no hits.But still was scary enough and i have no intention of closing BB on the surface