9 is a crap reload, go for 11/11.

Please see Adalbert's guide.

But the short answer is that only 1/3 of the accuracy is attributable to the gunner.
The other 2/3 is attributable to the FCS accuracy and the Gun accuracy. Blocking
Guns have mega accuracy revision.

Now for the gunner, the accuracy is determined by the gunners true accuracy ability
AND the gunners level. The level determines that sailor's accuracy cap. Once a
gunner has reached a certain level, they will always be capped by the accuracy cap
and not their true accuracy ability. The true accuracy ability growth will always
exceed the level-based accuracy cap growth. Depending on which navy and your
based stat and gunner type the acc cap could be reached anywhere from the 60's to
the 80's.

So +12 gunner will reach the cap a few levels before a +11 but once at that cap, the
accuracy of both will be the same.

Thus reload stat is very important, especially with the new higher reload cap.

Then I would suggest the 11/11.

Assuming you have a normal amount of vets/experts on your gunners, you should hit the
accuracy cap relatively quick, and the 12 accuracy base won't really matter at higher
levels (especially if you boost your gunners as well).

i'm going for bb on km

It depends which type of gunner you're going for (accuracy, reload, or AA gunners).

You'll eventually hit the accuracy cap for main gunners, but when that is depends on what
nation you choose and when you class them. I personally prefer matched pairs (i.e. your
11/11 gunners), as a difference in reload speed is a pet-peeve of mine. Yes, you can
combat this by using simultaneous fire, but it still bothers me :P

find atleast 12/10..