This question is somewhat related to
https://bg.battletech.com/forums/index.php?topic=81851.0Under 'Rotating the firing arcs' p105 TW:
Vehicles: Turret-mounted weapons in vehicles can be positioned to fire through any hexside, per the Torso/Turret Twist rules, page 37. Treat turret arcs as the forward arc, except that they are defined by the hexside at which the turret is currently pointing, not the hexside toward which the vehicle is facing.
Given that turret facing changes occur when declaring a weapon attack in the 'Weapon Attack phase' turret mounted artillery cannot be turned/twisted in the 'Targeting phase' (p147 TO: AR).
Considering the number of canon vehicles that have artillery mounted in turrets it would seem odd if the turrets can't be turned before firing (other than direct fire) but can still turn their turrets and have them flip back in the end phase pointlessly. Clearly there won't be any mention in TW of being able to turn turrets in a phase that doesn't exist in TW, or torso twist in TO:AR, so this seems an artifact of having the rules separated in the way they are.
In the context of the changes to torso twisting to use TAG:
1. Is it the current intention to strictly prohibit the ability of artillery to turn turrets before firing artillery weapons?
2. If turret turning before artillery weapon declaration is possible, should there be appropriate wording added in TO?