Just installed GW, deck gun no more ammunition
 

Just installed grey wolves mod 1.1 while in base during a campaign. Left base and tried firing the deck gun for kicks and it said there was no more ammunition. The flak gun fired ok and torps fired ok. It's been a while since I played it, not sure if I'm forgetting something.

Click on the HE shell and you will have ammo
There are no AP shells in GW as no evidence of any uboat ever having any
Not that it makes a difference what shell it is as they are all pretty much the same in SH3

This is just one of the many reasons why I picked GW as my mod of choice. I've read many books on the U-Boat war, and AP just wasn't needed. Submarines weren't supposed to fight it out on the surface with armored vessels. However, firing at merchies made sense, if you're using HE.