I don't know if reload gunners and normal guns work better for UK/US. I've read about that but don't have experience. I would also remind that AA guns normally are lighter than normal ones.

From what I read I must say it seems you have done bad mistakes with your AA gunners too:
1.) AAW ability is nothing. Look for reload ability for AA gunners too.
2.) Don't class UK/US/IJN AA gunners when classing is available at level ~20 ! You cut reload growth by a lot. These nations have to be leveled as armed sailors until around level 70-90 and classed then for remaining good reload speed and getting them to the reload cap.

First of all, you have to understand that the Sailor AAW ability is currently disabled. AAW is that automatic machine gun fire you see whenever an enemy plane is nearby. Simply put, the only ability useful for any AA gunner is Reload.

Some nations are deemed "AA nations" which is usually fast firing and has medium-long range gun capabilities. So far I have seen KM, IJN, MN and US to have good AA capabilities. Gun reload speeds are built into the guns coupled with your sailor Reload ability determines firing speed. AA range is also built in into the gun, but it seems lower angle guns (eg. 25) will be able to hit planes at long range. To test them with relative ease, i suggest you download the Test Server client and experiment with different setups.

Delay classing your AA is usually nation specific. So far I only know that it should be done on UK and IJN only. Here's an explanation for it:

With UK at level 12 we class to Arm Sailor which gives +8 Reload, good.

Next is 2nd AA Gun classing at level 20, which gives -7 Reload, kills the reload stat, not good.

Next is 1st AA Gun at level 40 which kills the reload stat even more by -5 Reload, very bad.

Say we used a base12 sailor. At level 12 Reload is 20, level 20 its 13, and level 40 its 8. Slow growth for the Reload stat. But let us keep in mind that at higher levels say lvl100, the speed will be usuable. But thats so far off..

So we delay class it --- delaying the application of -7 and -5 that the 2nd/1st AA gun gives to Reload. So we stay at +20 growth every single level up to whatever level you want it.

Remember, delay class only on nations that kill off the Reload ability.

US: use  normal (Reload) gunners  as AA, dedicated US AA guns are not worth it to spend time on delayed classed AA gunners.

UK: If you're going to use AA guns at all on UK, delayed classed AA gunners are the better option ( class to AA very late, 80 is really on the early side), using normal gun(ner)s is an option though and easier, "normal"AA guns are quite on the heavy side.

IJN: Always use AA, and always delay classing them to DP, after lvl 90 you can start classing them. The lvl 64ish classing you see mentioned in some IJN threads is to be ignored, those are old numbers from before the reload cap was moved.

KM: Always use AA, class on time, but there is no real need to class further than AA gunner.

MN: Always use AA, uses normal gunners for the AA guns, so class on time

SN: Using AA is certainly an option. SD-2 guns still have too much range for AA ( 30 GA), with powerfull AA shells, if a little slow firing. Uses normal gunners so class on time.

RM: not balanced at all atm, not having tried them for AA, from what I've read the worst for AA. Uses normal gunners for AA, so if you want to try RM AA, class on time. If the AA fails, you can always use the gunners for PHH.

For UK AA is one of there weak spots, it's probably the hardest to master in the game.
 the there is a small up side all of UKs AA guns( I think US is the same)  are duallpurpose which makes up for them being harder to use some what. 

As for the ships they have that carry a decent to good AA battiery are the Emerald,Dido(it's remod), Edin, and county for cruisers while Renown,Repulse,Queen Elizabeth,and the Queen Vicktoria for bbs and UK MIdway.

In terms of AA gunners/guns you will need Good base reload stat +12 atleast, (+11 is some what ok but will take a good amount longer)  and wouldn't class them til 90 at the earliest.
For guns there are very few that are any real good, they are the Dual 4.7s ,  dual 5.25" Rp10s( the ones used on the real KGV and vanguard classes), and the pompoms (which take alot of practice to get good with) all uk AA guns do decent damage that I named pompoms do alot when you aim properly and get a good spread of shells hitting the planes.

rld-rld-rld usn gunners is overkill. Having an accuracy class in the mix is a better choice imo.