So i joined a test mission in my H39 for some reason and there happened to be an iowa there.  We decided to test our range against eachother.
We lined up at the same line from the start and fired.  Honestly, there was no noticable difference between the gun's range.  Maybe I had a smidge more.
Not only that but I was unable to one shot the test BB's at point blank unlike him. I realize it wasn't a formal range test, but still, there was no 
difference in range.

Now I know KM has its disadvantages, its not a perfect game but lets look at a few things

KM Disadvantages
-Lowest Submergence
-Low accuracy
-Largest Hitboxes
-Lowest Damage

KM Advantages
-Range (?)
-AA Guns (I love this)
-Good OH time
-Nice Reload Speed

Now those four disadvantages are huge, noticable, dragging disadvantages.  Pairing Lowest durability with lowest damage 
alone should have been a bad idea, but then to throw in the massive hitbox and poor accuracy? thats just mean.  

However, range is a huge advantage and I can see it being able to overcome the disadvantages, but Im just not noticing the range advantage.
I mean I should atleast be able to hit an enemy ship of my tier without being hit back.  

This being said, am I just not using my range effectivly? I have heard it is a techique that takes practice.  I have seen some h44's ducking and
weaving about doing well.  I think I understand the slingshot technique, but if someone could explain it in depth that'd be great.
Even so, other nations can use the slingshot technique right back at me too.  I don't know. Is it me not maximizing my ships potential or
is it the ship?  I try to engage at max range, but it is so easy for enemy ships just to overheat towards me and fire away.  And if there are two ships?
Forget it, range has no effect at all.

WHAT CAN I DOO? Hahahaha