oh you KM AA spammer lulz...
You need to aim first, then shoot <- the best ammo saving mode ever!
But since you are smart at aiming, you would figure out, that the longer range you have, the more efficient time for aiming is spent.
And yes, KM has long range AA capable guns with GA of 29 - that's what i'm using.
Or even with 28 GA, but reload is bad for those and huge gun space requirement, and main gunners requirement... - which makes them immpractical.
But still, the best AA ingame is on IJN, the variety ranging from 25GA to 48, variety of reload aa shell damage, and muzzle speed.
And exactly this variety makes IJN AA the best.
AA capabilities comparison (in brackets - major drawbacks):
IJN > KM > MN(low AA shell damage) > SN(slow muzzle speed) > RN(limited ship T slots) > US(low range).
I haven't tryed RM AA though...
And as for Moltke, it's a decent AA barge a.k.a. worth getting.