The 88mm shells were stored in a magazine below the floor boards forward of the control room and between the radio/sound room.There was also a quick ready ammo locker built into the deck near the gun. There was no ammo hoist so all the ammo for the deck gun and AA guns had to brought up to the deck by a human chain. The 88mm deck gun was not related to it's land based 88mm guns and no parts were interchangeable nor was the 88mm cartridges. Someone asked about the dangers of scuba diving on sunken u-boats with all this unexploaded ammo still aboard, Germany was very hard up for copper and brass so unlike most other countries the great majority of German "brass "( cartridge cases ) were made from steel with a brown laquer coating, all cartridge cases that I have found were rusted and rotting away.