Not too likely. Any armed merchant with a popgun has better aim than you do and you have to hit them a hundred times to sink them. One or two hits on the sub and you're testing out your swimming skills. Destroyers can hit you three miles out with no problem. Same depressing math: several dozen hits to hurt them, one or two and you're toast.
One of the lessons of SH4 is that deck guns should have been left at home to prevent six week wonder skippers from playing Rambo and getting 65 guys killed.
