http://www.youtube.com/watch?v=puK-8e_d27Q&feature=related
Unlike today with computers and such, back than you and 7 other guys were on the deck per mount. You had to make these guns fire, if you wanted to have any chance of making it, they had to fire.
Remember these are steel ships, when rounds and shrapnel land it makes a racket and bounces around with a vengeance. It wasn't uncommon to have not only enemy but friendly rounds bouncing around as the Japanese aircraft would fly low between the ships, and the excited gunners would follow them, often with friendly ships in the background.
Having been in one of these turrets its surrounded by a steel ring, lined with holders for these clips. The spent shells were mostly captured by this ring so after awhile walking would become quite challenging, 40mm spent shells are somewhat large, more so if the spent shell casings were mixed with blood. Remember steel ring, 7.7mm Japanese rounds would bounce around in a horrible manner.
But you had no choice but to keep the guns firing, the Japanese if there aircraft were damaged would try to fly into the ship. You had to knock both wings off to prevent this. So no matter the cost you had to keep loading. The enemy aircraft would often use the tracers you sent up to get the position of the ship, and would follow them right in with an attack or suicide run. Either way you had to keep the gun firing.
Brave souls these guys were.