In the Greyhound movie, we can see a black messmate (or is it "messman"?) Cleveland regularly bringing food to the captain. When the U-boats attack, there is a moment, when we can see Cleveland passing ammo to the guns.
Towards the end of the movie, we can see that the ship has been hit in the gun turret and one of the victims was the previously mentioned messmate Cleveland.
-Direct hit on mount 43, sir. Damage Control reports fire, abaft frame 24. [...]
-Who are the dead?
-Pisani, gunner's mate, third class. Marx, seaman, second. Cleveland, messmate. Took a hit at the portside 40-millimeter gun tub, loading ammunition, sir.
Would someone who is basically a "navy waiter" really work around guns during the battle? I would think that handling live ammo would require certain training.