Does the firing arc in the card text relate to the primary arc printed on the front of the base like in secondary weapons or is it the full 360?

Cheers.

Turrets don't have a 360 degree firing arc, they are allowed to target ships outside of their arc. The only firing arc they have is the regular, normal one all ships have. It's just that in most cases they can ignore it. Tactitian is one of the cases they can't.

Also, contrast with the firespray which DOES have an additional arc printed on the ship card.

There is no 360 degree arc in the game.

Turrets are allowed to fire outside the ships arc. The Firespay has 2 arc's, for and aft. But when ever a card refers to the arc, it means the printed arc on the ships base card.