Ran thru the first part of my career with the deck gun aft. I was able to use it quite effectively but if the enemy was foreward had to engage at an angle allowing the gun to target either the starboard or port side. Once I graduated to the Gato and was able to install it fore I did so. Now I can engage from straight on with alot of latitude on attack angles.

No regrets here. I aggressively use it for surface attacks with defenseless enemy vessels or finishing off damaged ships.

Up front for me. :)

I usually go with aft mounting, this way I can (in theory) run away full speed while also plinking away with the deck gun. Worked great in SH3.

I'm not sure if it's modeled in game,but later in the war they would often mount a main gun and an AA gun on the 2 hardpoints. (1 forward 1 aft). I think the AA gun was another 40mm but I'm not sure about that.

I noticed it too.....
I'm a bit confused, is this a known bug?
I made a search but was not able to find the answer
EDIT: found the answer.
It is a known bug
See here
http://www.subsim.com/radioroom/showthread.php?t=111315