Once capped on RLD, the D variant is about 1/10 of a second faster rld, and shorter range
than the 3/70 Ns. Try what you like but take the best range/rld for your buck.

5"/38 mk38L. Good reload and damage, best range. Golden angle 36.

3"/70 mk23N is your only other choice. Heavier, slightly less range, but lower space
and faster firing. Golden angle 37.

The other guns that have this much or more range are either much larger and slow
firing (6" duals) or they have crap for shell damage (5"/54 guns).

As you see differences in gun types here,

I prefer the 3/70D's Golden angle 39, since they fire so fast you can put a wall of AA up.
If you want a more accurate AA use the 6inch DP's, or if you want balanced the 5/38s

The above posters covered the gunners. I'm partial to the 5"/38 Mk 38 L (golden angle
36). ...and 6"/47 D (golden angle 32) on the Guam. >_>

12 REL classed a REL>REL>REL is a waste. If you don't want any accuracy in your AA then
get a bunch of 10 rel/12 reps and class those as REL>REL>REL.

I do agree with the 3"70's though. Fast, lots of ammo and do decent damage.

+12 Rld saliors classed as triple reloads. 3/70 Ns golden angle 37.