USS Iowa Gun Turret video

I had the opportunity of touring the Missouri on her final voyage when she docked at Fremantle or it may have been Garden Island some years back. Same class as the IOWA and since I haven't spent much time around large calibre guns of any kind, I was amazed at the firepower. I think the main guns of the same boat. were featured in  the "if you could turn back time" by Cher video clip.
 
Amazingly, the tech had been around for some time. I was watching a documentary recently on the Jutland sea battle which showcased the WW1 Dreadnought class Texas with 14" guns and while not intending to be punny, I was blown away by the sheer explosive power available back when she was commissioned. Not that Texas had anything to do with the Jutland battle but she is the only surviving dreadnought class ship. Her 14" guns are not as big as the more modern IOWA but she was developed something like a quarter of a century earlier.  
Then I did some research and found that The PoHM's (Prisoners of Her Majesty), during WW1 developed an insanely powerful 18 incher.  military.wikia.com/wiki/BL_18_inch_Mk_I_naval_gun. 
With 690lb of cordite behind it, would send a 3300lb shell a similar distance.  Didn't get much use though with less than 100 shells fired in anger but considering each shell weighs about the same as your classic American muscle car from the late 60s/early 70s, it really puts it into perspective. Poor bastards on the receiving end.