It addsmore more shell spotting range and longer gun lines. Eventually...around bb3/4 you going to need to start shaving sailors off of him so your gun lines are not too long.

Where you heard that from? Which channel ?

Yeah, the only things that affect gun range are the type of gun and the ammo weight. Outside of that you can't change your range.

Vetting/experting your BO only increases the length of your aim lines, which helps with accuracy and guaging range, recommend you try to keep your lines the same length as your max range. I think BO ability also increases view range and the range you can detect torps but I can't remember for certain.

People who don't know anything are the ones that talk the loudest in games.

But you will have a problem when the guidelines are much longer than the range of your guns. That makes it difficult to make a hit with your first or two shots. You will have to reduce the number of  sailors of your BO to get a more or less similar lenght!

I've worked to this solution for a long time and it works for me

Elite Potentila with boost  90/100 vets

Normal +14 sailor with boost 110/130 vets

with Experts at max 

Hope this helps

my experience is that you dont need to boost your BO Pot 15 + 109 Vets and more experts, cause the same,but your guideline be until at a higher level (90) you will see your shell hit at the and of the guideline (max range)