I think that KM AA ships are 2, with different features each one.
Emdem: Have 8 slots ans you can fire 6 to each board side at the same time. As the slots are better distributed in the ship can cover more area, but deal less damage in the same are. As those slots are the main ones, when turns the ship have to re. position your guns to accurate fire. It´s also a relative weak ship compared to Molkte
Moltke: Is a strong ship, and as concentrate all guns in mid ship zone can wipe out a full DB´s wing in seconds. Also, have son extra slots to put HH, just to help chase enemy SS.
Also, as AA guns are un R slots can shoot even you are turning. This is a helpfull characteristic.
I tried 3 guns, 3.46", 4.1" and 5".
The 5" if the most lethal, but guns and ammo use a lot of space, so I switch to 4.1 some time ago. The GA is almost the same as 5", I try 0,5 degree up from 5" GA and works fine.
The best feature of 4.1 is you can load a lot of ammo, that is helpfull passing 7 minutes of battle.