I'm not sure how they reload it either, but it's got to be some sort of quick reload system. They aren't going to put men at risk, by keeping them on deck for extended periods of time. It's probably belt or chain fed, and loaded up from below. Or at least I would hope they don't expect soldiers to climb up those steps when the vessel under fire. And you are correct about the last resort use. Also, I think it's a pretty large round, for full auto, like 20mm, which isn't quite an inch, but much larger then the old basic Browning M1A2 .50 caliber machine guns they used in Viet Nam, and earlier, against planes and such. I think that it would look much better with some sort of paint on it. Like a flaming skull, or a Jolly Roger. Something that screams, 'YEAH, WELL FUCK YOU TOO!!'.