The Big Ship Down Guns

Moment arms. Centers of gravity. Achy-shakey-breaky 57mm mount ... yes I understand.

However, what do we know from history? We know that once the shooting starts, all your ships are undergunned in number, range, and redundancy. 

We add as much as we can after the losses of a few units - or as the Royal Navy did in San Carlos Water - if you don't have time to head back to the yard you line the decks with every weapon including infantry rifles to throw lead at the enemy and apologize later for not coming to the fight with what you needed.

So, we have the Pocket Battleship sized and poorly classified DDG-1000 Class before its first deployment already ... well ... making an adjustment. Via our buddy Sam at USNINews;

The Navy has replaced two 57mm guns planned on the Zumwalt-class guided missile destroyer designed to fight off swarm boat attacks with a smaller pair of 30mm guns, Naval Sea Systems Command (NAVSEA) told USNI News on Monday.

The trio of Zumwalt-class ships were originally designed to field the BAE Systems MK 110 close-in gun system (CIGS) — a gun used on both classes of Littoral Combat Ships (LCS) — to provide the ship’s company options to fight off so-called swarm boat attacks of the ship as part of a 2005 critical design review (CDR).
...
Following a 2012 review the Navy, “concluded that the MK46 was more effective than the MK110 CIGS,” according to NAVSEA.
“In addition to the increased capability, the change from MK110 to Mk 46 resulted in reduction in weight and significant cost avoidance, while still meeting requirements… that will provide a robust rapid fire capability and increased lethality against hostile surface targets approaching the ship.”

What are we trading in our secondary gun armament?

The 57mm Mk 110 fires a 220 rounds/min at range of about nine nautical miles
...
The 30mm Mk 46 has range 2.17 nautical miles and fires at a rate of 200 rounds/minute,

Yes; smaller round, lower cycle rate, shorter range.

And again - for a ship the size of a Pocket Battleship - it will only have two (2). Good things guns are never CASREP'd, jam, or .... sigh. Another exquisite plan from the age of transformation fails to transition from PPT.

The things we plan to send out Sailors to engage in war at sea with. Amazing.