The leone does NOT have the range of a battleship. Thats been proven by the release of actual numerical range.
The Leone is very different from most destroyers and especially Tier 1 Destroyers. Other destroyers are nearly indentical, and have ranges of about 1500 with 6inch guns. That may seem odd but the special EOL 6inch guns were ment to be a secret high velocity gun during world war 2.
the Leon is balanced as it has THE WORST weight, speed, and even the only dd1 that has a 50% speed decrease, unlike most ships which only lose speed at 40% hull points. A few hits and its crippled.
Even if you do equip the 6inch guns, you cant equip secondary weapons due to weight, and because its a destroyer with limited weight you cant mount skilled sailors.
Bottom line, the Leone DD1 has long range guns AND NOTHING ELSE. Get over it.