i do not believe so. this is because the accuracy stat has a fixed cap at which no more vets will make a difference to your spread. so once you hit this your spread will never get better except for those occasional lucky shots. the +1 acc doesnt affect your gunners but your FCS so thats why your acc somewhat improves. thus a seaman which provides extra ability would make no difference on an ability capped gunner. now if your gunner isnt acc capped then yes it would make a difference. this is why seaman are mainly used for boosting fighter ability as it has no cap or if it does it is almost impossible to reach, but i dont believe it does.

you can't mount any tuning item on all bb6 and cv6