for aa gunners = mostly use is the pompoms

for rel gunners = 5.25" RP10 is likely popular, you could go D or L(for longer range)
or
5.25" QF (longer reload though than RP10)

I did an equation and the 5.3 duals, Level 48 are 50% less powerful than pom poms. based on Reload, barrels, and damage per AA shell, but Range is better on the 5.3s .. time to have a test of this. :P

Reload of Pom Pom. : 440% of RP10
Damage per shell: 13% of RP10
7 barrels vs 2: 350%

Pom Poms are twice as powerful... but the golden angle is 51...
RP10s golden angle is 36 so they are more effective, but they aren't as powerful...

Conclusion, don't use UK for an AA ship... lol

i hate useing the pom poms if you wanna use the AA guns like purpose AA thing when you class your sailoirs to use it(i dont remember the name) delay class it till you get lvl 85ish if not just class your gunners as reload as your be doing even with your main gunners and use RP10s i belive? they are decent

Pompoms golden angles are not 51. They are around 44 and they are quite usable.