Yes, increasing the number of Vets and Experts will help with your issue.

There is a new feature that will also help. When you are in shipyard and you have the "ship" tab open, not the "crew" one, look just above and to the left of your armament list and you will see two numbers labled something like "guideline length" and "gun range" (could have that wrong), but they are there. 

They will tell you your shell range and how far your guidelines reach. Aim to get those numbers close to each other. Use the appropriate guns for your ship and add vets and experts to BO until your guideline length is close enough for you to the shell range.  

Ah, excellent, I hadn't even seen that feature. Thank you very much.

If it's only the AP shells you can't spot, you aren't using the correct HE shells.

LHE and AP have the exact same range. If you can't spot 1, you shouldn't spot the other.

Using normal HE or heavy HE shells on a BB is an absolute nono, range is everything for BB's.

Use LHE in the 1st locker, AP in 2nd. Mixing ammo ( some guns firing LHE, some AP in the same salvo) is not the smart thing to do.

I've been wondering whether or not people use LHE or HHE

Save the HHE for Blitz. Although, some people would even advise against that. I like having the extra punch in Blitz given most eveyone's spread is terrible in Blitz given the lvls, you'll have no problem getting in range.

LHE is really the only viable option in GB. As danita said, range is everything in a BB. Keep a bind of AP in the secondary and load up LHE in the primary locker. It is convenient to have your HE and AP shells flying the same distance. Only achievable with LHE. 

I've started using them and since become a much more useful contributor in GB ;)

Though I seem to have committed several cardinal sins in making my gunners accuracy gunners and classing them on time. Really should have read through the forum before starting. 

At this moment I am working on a Battleship guide for NavyFIELD forums. I thought I was almost done, but I see questions coming up that I forgot to cover....

Like Danita said; range is very important. I use it with CAs and sometimes CLs even in blitz to outrange people (: