Why a U-boat gun victory over an escort would still be a trap

Could a surfaced U-boat historically defeat an escort in a gun duel?

A lucky victory is considered theoretically possible, but no historical example is identified. Damage preventing the submarine from diving would leave it exposed to further escorts.

A U-boat is a comparatively poor surface gun platform against a purpose-built escort. Damage to its pressure hull can make submerging impossible, and 40 mm guns and machine guns are cited as threats alongside the escort's main armament. Even if a lucky shot disables one opponent, further escorts would leave the submarine exposed on the surface. No historical example of such a victory is identified in the reply.