You're right Tracker, it is definitely a house gun. Having once used 20 mm's @ 6,000 rounds per minute, even a 6 inch 12 gauge is a bit of a comedown.
Guess the moniker is too obvious; it's definitely NOT admiral. Landing on boats sounds like an idea a Kennedy might come up with. There were times I had problems with 10,000 feet of runway, while it held still no less.